********** lines opened on my contract

I have a contract with mtn, I bought a notepad. I pay R199 per month about 3 or 4 months back I got an SMS saying I owed mtn R1700 and something. I called mtn 808 number to enquire, they told me there were other numbers added to my account without my knowledge. They told me to go to the police station to get an affidavit stating that I don't know the other two lines and they should close them. I sent the affidavit to the consultant and she said she will send it to the ***** Dept. I waited for the response, they didn't respond. I called back and went through the whole process again with another consultant still there is no response. The money keeps growing they say I owe them R4767.12. When I call them they keep sending me to wrong departments. This is destroying my credit profile. I'm very disappointed with mtn.