MTN hand me over to Saya Recoveries but someone at MTN was changing personel details and doing ***** in my name

I'm having a really bad situation at MTN. I had a sim card router on contract at mtn. The ended december 2025. Mnt then called me and ask if I want to upgrade my contract, and i said no I I'm thinking of going to a new service provider. Then the person I spoke to said then let's do a month to month contract, she explained to me if I pay I'll get internet. I said great, sound good until I get a new router. So my understanding the contract is fully paid and then if want internet i make a payment. Last week I received a message from Saya Recoveries I have outstanding amount of R8379.20 at MTN. I firstly thought it qas a *****ulent message like these ****s. 30min later Saya Recoveries call me and explain to me that I was handed over to them from MTN as i own them money. After a long back and forth discussion, as u need to know how did they get to thus amount and where is the proof. It explained to me that i did not give the router back so they charge me for that and data that was used, and Saya Recoveries also put fees on top of that as they are handeling situation. I explaind that the contract was fully paid and it was on a month to month contract and was advise to call MTN. This is where it gets frustrating after calling MTN and spoke to four diffrent people a hour and half later i got hold of someone that can log into my account and see what is happening. And i explained to her everthing. This specific person was very helpful. After she investigated my account she realized that on my account my email address and contact details was changed. So they did try to warn me but those details was change so I couldn't receive anything from MTN. Then i ask her who change my details without my authority. And she got a shock I could here in her voice and said to me there is ***** going on on my name at MTN. She can cleary she after my contract there was a lot of activity on my account, but not allowed to geve me any details. I need to open a case of ***** at the police station. And send MTN ***** department the case number. In the first place MTN is busy with my account and making changes without my approval. Now i need to open a case of *****. I work 8am to 7pm everyday where will I get the time to do so. And secondly why did MTN no investigate this before handing me over to this Saya Recoveries. Then when Saya Recoveries called me today. I explained the situation to them they say they don't deal with MTN after they handed me over. I need to send them all the documents from MTN and the case number before they can help me. What do i do in this situation? I'm furious here this is a matter between MTN and Saya Recoveries.