unauthorised debit order taken from my account.

iam highly dissapointed in mtn been a loyal customer for almost 20 years. i cancelled my contract 14 November 2021 last debit order due at end of November which i confirmed with the consultant , she even provided me with a reference number. and confirmed no debit order will be deducted after November. just to get and sms this morning the took again and even more then my contract amount. No this debit order were unpaid and now my bank charge me for an unpaid debit that should have been cancelled by mtn...