MTN giving no feedback as said they will

I wrote an email to MTN (See below) and I jave not received any feedback apart from an automated reply that they will give feedback within 3 working days. Still nothing, 18 days later.

"I would like to report ***** that happened on my account please.

This evening, 4 February 2021 at about 18:12 a person phoned me from ***. He said that he is from MTN and that a request from was received on my account for a sim swop. He asked if it correct and I said no, I did not ask for a sim swop of any kind. He mentioned a name and I said that I do not know of such a person.

He then said that I should receive a sms with a OTP that he requires to close the case and not approve the sim swop. This sms was received from MTN (shows as MTN on my phone. No number to it). As it looked legit, as it is from MTN, I read the OTP to him.

Just as I hung up the call, I received an sms from MTN136 stating that I have transferred R200 to +***. And just after that sms, I received another sms from MTN136 saying that my usage limit has changed from R120 to R2710. I have not asked for this. I went onto the app but see the spent usage limit still R120, and the bill is R 2710. Well, I know went to search this number on truecaller, and it seems to be a MTN *******."