Complain

In 2017 I had contract with mtn and during the last four months of my contract I lost my job but within three months I got a new job and at that time mtn had already send my account to one of there collect saya collection then I paid it off then forget about is this I was looking for a new phone and mtn told me that my account was never closed it actually accumulated over 15000 in interest which is sad since they the one WHO set the contract rules and terms