Mtn contract not happening even after calling, smsing, emailing and dming on Twitter

My contract ended in April, I sent an email requesting for the insurance to be cancelled but the contract was not. My account is debited every month yet I have been sending out communication for over two months asking for the contract to also be cancelled. I have called, they play a jingle and you hold close to 15 minutes. I have emailed, its an unending back and forth with no viable solution. I finally tried Twitter dms, to this day no feedback or a call or update but you watch them debit my account month end. The sad part is my credit score is being affected by these ******* debit orders and I incur bank charges for debit orders that bounce. Their complaints department reiterates one message as if it's an automated bot and offers zero to non-existent solutions. Somebody please help me