MTN is incompetence

I opened a contract with MTN in 2013 received the phone, with in the 7 days waiting period I realized I don’t want the phone anymore after 2 days I called the call center to come collect the phone. The courier came and collected the phone. After six months I started receiving calls from MTN that I should pay my account I spoke to the manager we fixed the problem and they realized it was a. Error on their side they wouldn’t continue billing me and the contract would be canceled. Now Six years later I received a call from MBD credit that my MTN account was handed over to them. They advised that I should go to my nearest MTN branch they are just useless they tell me to call Call Centre