Debit orders running on cancelled contract??????

Do not use this company. I've had hassles with them from the beginning. I requested for SADV to cancel my data contract in November 2018, I was told that its needs 30 days notice and that the Dec debit order(which is a payment in advance) would the last one and from January the data contract would be cancelled. I WAS DEBITED NOW IN JAN for Jan Services!!! WHY has contract has not be cancelled as the account department confirmed??? I've emailed and tried to call and no response. They've taken my money when the contract is meant to be cancelled. No communication or explanation.