Vodacom and their bad service

I had two contracts with Vodacom and paid them up before the contract ended. I did not renew the contracts and asked that they be cancelled in September 2018. A final payment of R370 had to be debited from my account as I had a debit order with them. Unknown to me, they did not debit this amount as they were supposed to and the account went unpaid. When I tried to open an account with another company I couldn't as something on credit bureau hindered that. That's when I investigated this issue and to my surprise Vodacom had handed me over to MBD attorneys, without even letting me know I owe them. I now have a bad credit record and cant open any accounts nor get any credit cards etc. I went to Vodacom and they tried to contact the call centre but couldn't and instead gave me MBD number and said sort it out with them. Vodacom has caused big problems. They haven't sorted this issue out even after I have made the payment. MBD can't even pick up a record of me on the system for Vodacom, so how do I get my name off ITC. This makes me very upset!!!!