Avis Budget Rent A Car Budget Car Rental did not provide promised service, gave me a problem, didn't help fix the situation Internet

I reserved a 7-passenger mini van yesterday at 5:30 in the afternoon.  It was reserved from today to next friday.  I revieved an email confirmation with confirmation number, estimated cost, vehicle type, etc.  When I go to pick it up today, the attendant says they do not have a van, only cars available, and that it was my fault for not confirming the reservation.  The email was a confirmation of the reservation, it said so on the email, but the attendant simply kept stating it was my fault.  When I mde the reservation i was not informed I had to confirm the reservation, and since when do you confirm a resrvation for a car rental after you've made it?  You make the reservation, pick up the rental at the designated time and that's that.