Unauthorized debit orders

Unauthorized debit orders going through any day of the month. I have an arrangement that I've always honored but they keep debiting my account & that is causing unpaid debit order charges on my account. I have sent emails and WhatsApp texts but nothing seems to be done. I was told that the account needs to be up to date in order to avoid such debits. Yes I canceled two trackers & made an arrangement to pay but why debit on days that I don't have an arrangement on? Their email & WhatsApp replies are unprofessional & condescending.