Cancelation of contract

I have cancel the contract with mtn 3 months back ref no *** even the contract has not cancelled. When I call 135 they transfer me to retantion department and there is no one who answering the phone that side I hold the whole without being assisted. So this month I reversed the debit order, yesterday they suspend my number the said I owe them so who can assist me with cancelation and refunds from the previous month that they have debited into my account. So I want my line to be u suspended working as soon as possible, I can be contacted on this ***