Debit Order Mess!!

Very unhappy with budget! I called them to tell them to check that my debit order goes off on the last day of the month since it was debiting wayyy earlier than that, and causing overdraft costs. Consultant tells me the issue is with my banks debicheck. I went to check and the bank has registered a mandate with Budget to debit on last day of the month i.e. 30/31st. Guess what happened today!? on the 26th of the month, a debit order just went through ! How is this possible because month end is only next Wednesday. This is frustrating, it seems they didn't listen to their customer and dismissed me, as long as they get their money! Nxa. Been with them for 3 years but considering moving to another insurer