Slamming: your cellphone line changed without your consent, and how to reverse it

Slamming: your cellphone line changed without your consent, and how to reverse it

One day you get an SMS welcoming you to a network you never chose, or confirming a number port you never asked for. Or your airtime starts disappearing into "content services" you never subscribed to. Your line still works, but something on it has changed without you. That has a name: slamming, changing your service or your provider without your consent. Nobody may do it without your agreement, it is more common than it looks, and it can be fixed if you act fast.

How do they change my line without me noticing?

It almost always starts with a pushy sales call. The typical pattern:

1. They call pretending to be your current network ("we're calling from your network, we're upgrading your contract") or an independent "deals" agent.
2. They ask you to confirm details "to verify the offer": your full name, ID number and address, sometimes your bank account number and branch code, or the one-time PIN (OTP) that has just arrived by SMS.
3. With those details and a recording of you saying "yes" to vague questions, they put through a new contract, an upgrade or a port to another network, and present that recording as your consent.

Sometimes there is not even a call: once your details have leaked (data breaches, online forms, directories), a dishonest sales agent can put the change through and pocket the commission. That is why slamming often goes hand in hand with the "yes" trick: a recorded "yes" signs no contract, but it is used as a prop to make it look as if you agreed.

There is also a version that does not touch your contract at all: content subscriptions billed to your airtime. One tap on an advert or a pop-up, and a service you never really chose starts taking money from your prepaid balance or your monthly bill, again and again.

How do I know I have been slammed?

The warning signs:

• A welcome SMS or email from a network or company you never signed up with.
• A porting or sign-up SMS you do not recognise. Do not ignore it: it is proof that something is moving.
• Your network stops billing you, or you get a final bill with a penalty for "early cancellation".
• Airtime or data that vanishes faster than usual, or SMSs from short codes about a "subscription".
• Changes in your online account or app, or you can no longer log in with your details.
• Your cellphone suddenly loses all signal while people around you still have it. This one is urgent: it can be a SIM swap, where criminals move your number to their SIM to receive your OTPs. Call your network and your bank straight away, from another phone if you have to.

Golden rule: any message about a change you did not ask for deserves an immediate check. Call your network (on the official number, which you looked up yourself, never the one in the suspicious message) and ask whether anything is pending on your line.

What do I do to reverse it?

Act in this order, and in writing whenever you can:

1. Contact your network (Vodacom, MTN, Cell C, Telkom or whichever you use) and explain that you never authorised the change. Ask them to stop it if it is still in progress, to cancel any contract or upgrade you did not sign, and to switch off content services you never ordered.
2. Complain to the company that signed you up, in writing, and ask for a reference number. Demand that the contract is cancelled without any penalty and that everything charged is refunded. Ask them to send you the proof of your consent: the signed contract or the recording. If they cannot show that you clearly agreed, you are in a strong position.
3. Do not pay penalties for a contract you never signed. If they threaten to list you with a credit bureau (TransUnion, Experian or XDS) for not paying, say so clearly in your complaint: a listing for a debt that is not yours can be disputed with the credit bureau.
4. If they do not answer or they reject your complaint, escalate. For cellphone and other telecom services, complain to ICASA, the communications regulator, through its consumer complaints process once your network's own complaints process has failed. For unwanted content subscriptions, you can also complain to WASPA, the industry self-regulator for these services. For other consumer services, go to the National Consumer Commission. Keep every document and reference number.
5. If they used your ID or details to impersonate you, also open a case at your nearest police station (SAPS) and ask for the case number. It strengthens every later complaint.

If the change came with money taken from your bank account, call your bank's fraud line straight away (the number on the back of your card); you will find more about getting money back on our blog.

How do I stop it happening again?

• Do not confirm details to anyone who calls you. Not your name, your ID number, your address, your bank details or any OTP. If they say they are your network, hang up and call the official number yourself.
• Answer with "Hello?" instead of "Yes?", and do not answer a stranger's closed questions with one word.
• Check your bills and your airtime every month, and your bank statements too. Slamming shows up there before anywhere else.
• Ask your network about alerts and SIM-swap protection, so that you hear about any port, upgrade or SIM change on your number.
• Report the number that called to sign you up: these campaigns target thousands of people, and the number usually collects reports in the spam numbers directory that warn the next person.

On sales calls in general: the National Consumer Commission is phasing in a National Opt-Out Registry, but consumers can only register from May 2027, so for now it will not stop these calls. Until then, ask each company to remove you from its list, and if it keeps calling you can complain to the Information Regulator.

Frequently asked questions

Is slamming the same as a change I asked for and then regretted? No. If you agreed to the deal and changed your mind, check your contract: depending on how the sale was made, you may have a cooling-off right, and the National Consumer Commission can tell you more. Slamming is a change you never asked for: you are not cancelling a deal, you are disputing a contract you never agreed to.

They say they have a recording of me accepting. Am I bound? Not automatically. They must show informed consent: who was calling, what exactly you agreed to and a clear acceptance. Ask for the recording and listen to it: many fall apart because the information was misleading or the "yes" was vague.

Can I go back to my previous network? Yes, you can move your number back. The company that took you on improperly should carry the cost of putting things right, so ask for that in writing.

How long does it take to sort out? Dealing directly with the company takes weeks. A complaint to ICASA or the National Consumer Commission can take longer. That is why you should start as soon as possible and keep every document: time is only on your side if there is a paper trail.

In short

Slamming lives on two things: your details and your silence. Deny it the first by confirming nothing over the phone, and the second by acting as soon as you see a sign: stop the process, complain in writing and ask for proof of your consent, and escalate to ICASA, WASPA or the National Consumer Commission if needed. Check your bills and airtime every month and report sales numbers in the NoCall spam numbers directory. You will find more advice in our step-by-step guides.