debit still goes on after 30 months

My contract has ended 5 months ago,still mtn debits my account. I have tried to talk to consultants,they refer me to machine answered self service #808....i tried it but it didnt work...I went back to provide feedback,but I was told that mtn head office was on strike that could take a whole month,i was so angry and decided that I will reverse the payment once they debit.....i cant go on like this....