Very unhappy Client

I have been with MiWay for many years, up until I purchased a new car at the end of last year. I was forced to move insurance since MiWay could not accommodate a premium to my needs. In March of this year, I decided to call MiWay to see if they could beat the premium i was paying or match it since i was very happy always with you guys and trusted MiWay with my car insurance. My debit order date was agreed on the 31st of every month, as also stated on my policy. Now, this morning I wanted to make a purchase, and there was no money in my account. A whole week before the 31st, you guys debited my account. I called my bank, thinking it was ***** but in actual fact MiWay ran their debit order and took what was left in my account, which wasn't even the full premium, and now my account is in a negative. When i spoke to a sales agent, he mentioned that the accounts department put my profile in a NADO Tier or whatever they call it, allowing debits to run 5 days before. This was never communicated to me, it was never agreed upon by me as a client, and I would like a formal complaint laid, and I want my money refunded immediately. This is utter bull**** from a company as big as MiWay to just take without notice prior to debit order agreed upon. This has now put a sour taste in my mouth with MiWay. I want this sorted out ASAP, and I want this **** NADO removed from my profile as I have no clue why it was there in the first place.