MTN bad service

I called MTN requesting for my Settlement letter on my contract that is handed over but they told me they don't know the legal where my account is handed over to and i want to clear my name i made 5 calls the whole day but no assist very bad service am really stuck and i don't know how i can pay my account because they are useless the last person i spoke to is Matidiso she's was worse can someone tell me how i can deal with this