billing for a ported sim that was fully paid up

good day[let me start by advising you that i am hard of hearing on cell phones so emails are preferred]i had a sim only contract with telkom mobile[*** m j recrosio] and the sim stopped working and telkom said i must drive from umtata[my home]to east london to do a sim swap,i then was called from telkom cape town to do an upgrade and i then gave notice to cancell the contract[it was older than 24 months at this stage on a month to month basis]and up todate as i had a monthly debit order in place-they said it would end after 30 days and a month later[2-6-15] i ported the no to cell c prepaid at umtata and have been using it since then-meanwhile telkom debited my account for r1500 3 times and around r18000--i reversed these payments at the bank and told the el telkom branch and they promised to sort it out.i also tried the telkom web site but had no luck-i was then handed over to nudebt [put on credit bureau]and emailed them around 4 times without any response--they keep smsing/phoning me to pay .please help me to sort this out-its causing my name to be spoilt and incurring bank charges=thank you m recrosio