3 Years Later...

I have an MTN contact years ago which i was paying for, i made what i was told was my last payment at the MTN at Carlton centre and was advised the account was concluded. in this week i get home and my gran tells me to call MTN as they called and left a message for me to call them back. i called through today and was told i owe almost R5000.00. i was never notified in the past years that is account exists. my monthly payment was R299 and now im expected to pay R5000.00. MTN claims that they were unable to reach me, amazingly they used the same details to reach me now that i had registered my contract with so how MTN was unable to reach me is beyond me. the sad part is i called MTN to enquire what is it they wanted and i spoke to the customer care agent who told me he had no answers for me and he put me through to the finance department of some sort. while discussing this isue with the gentlemen there he cut the call on me. i need MTN to call me cos this isnt funny especially R5000.00 later.