***** department not working

My name is Sibongile Ndlovu my number is ***. This number has always been a prepayed number but I've received a invoice statement with account number A*** and I'm owing mtn R1460.05. I have called mtn customer service and spoke to over 5 consultants who couldn't help me but one told me there is a dealer number that proves I activated a contract last year December.... I refuse to be ********** by mtn my last contract with mtn had issues that it took hello Peter to intervene. I'm hoping hello Peter will intervene even now because mtn is struggling to help I'm hoping to speak with a competent person with regards to this issue.. I'm not working and won't pay for a contract I don't know...