Mtn Contract bad service

Took a 2nd contract(rooter in may) but I was upgraded on the contract I initially had.I called the company and I was told to return the rooter for the matter to be resolved of which I did but the matter still persists,it's now mid July and I'm still calling mtn to get the matter fixed. Early this month my line was suspended due to money they say I owe as a result of a contract I know to be cancelled, I called in and was reconnected now today I receive an SMS saying I owe them another amount for 2missed payments called in and I'm being sent from pillar to post on this matter(I have made more than X10 calls and E-maisI.My last call was even dropped by a sales agent. This is so annoying, to think I've been with the network for more than 10years....The error was made by one Cynthia Shambhala who's promises to have the matter fixed were unfulfilled