Cancelled contract debits

I've cancelled the contract in 2019 Nov and went to The Glen Branch and Trade route mall branch. Every time they tell me that the issue is resolved but they still debit every month for the data that I don't even use. My bank account is always in arrears and I can't use it because immediately money is transferred to the account they debit and I have to make the reversal. Please help. This issue has prolonged for too long.