Breech of Contractual agreemnet by MTN

My contracted agreement period lapsed, they continued deducting even though I had made attempts to cancel the contract in various branches.they said its done by Head office, I must wait until my turn comes...the money will be reimbursed once they eventually cancel in Head office . The deduction continued, I then changed my banking details, they listed me as a defaulted.

They are deliberately making cancellations impossible so that they may undully deducted money outside the contractual agreemnet, without consent.