MTN I want to clear my name now

I had cellphone contact with MTN in August 2018, somewhere along the line, MTN stopped debitting from my Account. On the other end I'm assuming my contract has expired. Next thing I get phone calls from VVM lawyers stating that I need to pay R 3000 + I know nothing about. Now my credit is damaged, I'm struggling to buy a car. When I contact VVM and MTN, They tell me they can't find my contract. Now I'm going back and forth with the companies trying to get the bottom of this but no one is willing to assist me. I called MTN and they gave me this Ref number :***, stating I'll get a call back from their legal department within 2 business working days , 7 days later no one has contacted. Can someone please help me, I need to clear my debt and mostly importantly clear my name from the credit bearue.