cancellation

Finished my contract in July and cancelled my insurance of which the last payment was in August, iv sent numerous emails to MTN pleading with them to solve this issue but they didn't, in their response the fist time they said i don't owe MTN anything my last payment was in August, now they are busy sending me billing statements and telling me that i owe them. I'm even tired of calling their call center because it seems like they don't know what to do anymore. MTN has the worse service ever.