Miway debits our bank account on dates not agreed

My husband took out car insurance a couple of months ago with Miway and it has been a pain ever since. My husband gets paid on the 27th of the month but Miway starts debiting his account from the 24th and this happens almost daily until the 27th. This has cost us a lot in bank charges due to the fact that there are no funds in my husbands account before the 27th of the month. This month the debit orders have started going through today and by the time my husband gets paid next week we will be owing thousands in bank charges.We have tried calling the call centre but no one answers and I have tried to get them to call me but no one does. Somebody please help me cancel this insurance it is costing us too much.