Unexceptionable customer service

My mtn contract expired in September 2015 and I called in September to cancel it and change over to pre paid! Instead nothing has been done since then...I've called over 10 times to cancel this contract and change over to prepaid... None of the consultants have gotten back to me, my account is still being debited and in November I was debited twice and I know my account wasn't in arrears as my debit order runs every month...what is going on with you unprofessional staff! I want my money reimbursed and I want this contract stopped and changed to prepaid or else I will take matters further and sue mtn, I have no issue with going to court!