Reservation and a debit order.

I am extremely unhappy with Avis. I rented a car from them for about 3 weeks. When I made the rental, they reserved money from my bank account for the rental. Now, after I have returned the car, two weeks later, I see that there is a debit order from Avis that almost cleaned up my bank account. Mind you, the reserve money is still reserved and I am unable to use it. Now, my other debit order get rejected because of Avis? This is highly disgusting and very inconveniencing. 24 hours later, the reserved money is still not available in my bank account. What if I had an emergency that needed me to use the money? Come on!!!!