Useless bank

I recently took vehicle finance with the bank. My contract says my debit order is support to come of on the 30th of every month. Suddenly a debit order comes off on the 17th which was not honoured. I called the call centre to enquire about it and I was told that it would be processed in a few days. 4 days later there's no payment coming off. I called again and was told that it will be escalated to the agent to sort it out. 3 days later still nothing. I then receive a call from attorneys that I am in errears and they are demanding 2 months payments of which one they are not entitled to. I am so frustrated and angry. When I want to excalate the matter no one wants to help. The bank is useless and the attorneys are useless.