We prepaid for a full-size sedan through a travel company. Upon arrival at Avis at Portland, Oregon airport, we were informed that a car that size was not available, and that they would give us an upgrade. Imagine our shock when we were later billed an extra $30 per day for 10 days, plus taxes and fees. We were never told that the upgrade charges would apply. When I contacted customer service, I was admonished and told to pay closer attentio to my contract. I am very angry, and I feel that this is a tactical practice to make money at consumer expense. They should cancel and refund my original contract, and then draw up a new one.