Bad service

I have to month to month contract with mtn,first the person who did the application for me told me they don't take debit from the bank I use,which I found out is a lie.i made payment with the reference they gave me 12days later they still tell me my payment isnot reflecting.after I sent proof and speaking to 5 different agents.received sms my payment has been allocated 6days later they suspend my line again saying thy ddnt get my payment.m tired of their treatment.if they don't restore my line m canceling this stupid contract cuz they so *********** and don't value their paying customers