Acc is paid....stop adding interest

March 2014 I took an cell phone upgrade. May 2014 the phone was freezing and I sent it back for repairs. When I called MTN about the phone I was given the run around, until I stopped paying my account. The phone was with them but I was billed for services that I was not usin. August 2015 I called MTN to settle account. I paid the full amount and sent proof of payment. When I called to find out when am I getting back my phone. I was told the account is with norman bisset.<br> When I called the norman bisset I was told I was supposed to pay the money to them not to MTN and that they can't help me as MNT has to transfer the money to them