Mtn Westgate is horrible!!!!

I opened a mtn contract with yolanda ntsala at mtn eastgate in the 13th of January, I later canceled the contract with Nombulelo Mbengo on the 24th of January, she made me pay a "cancellation fee of R421"she also assured me that I didn't owe anything else,she even said "if mtn debits ur account u can reverse it,sheeven changed thenumbertopre-paid. It's may now and I'm still getting billed R721,the store said I mustn't pay they will investigate, but they don't give feedback, I think they are totally inept,disorganized, *********** and rude.even bruce moerane the "manager",has not even spoke to me.i want this resolved!!!!!