Thrifty Car Rental Overcharged

I acctualy booked a car online through Expedia for a 4 day stay in the SF bay area. I needed just a basic transportation car to get from the airport to my destination and return so I booked a economy car at $27 per day. My total charges were to be $258 including ins., they required a deposit of $186 of witch I paid. When I got to the rental car counter I gave them my info and they proceeded to complete my reservation (this was after waiting 2 hours inline to get to the counter). I then picked up the car and went on my way not really paying much attention to the paperwork at the time being totally annoyed after the long wait I made it to my destanation and thought nothing about my charges because all of my charges were confirmed on my original booking through Expedia. After returning the car on the day I stated in my contract I was in a slight rush to get to my gate to catch my flight. During my flight I recieved my final bill from Thrifty by email but not having wifi I wasn't able to open it untill I landed hours later. After reviewing my charges I see that they automatically gave me a upgraded car that I NEVER requested and a complete additional day of rental charges for being 30 min late upon my return. Also the deposit from Expedia was not deducted from my total. After checking with Thrifty they said I reqested a larger vehicle witch I did not! After checking with Expedia they said that the total from Thrifty was on top of my deposit, my total charges went from the original quote of $258 to over $600. So it was one thing to get charged for an additional day of complete charges including all of the BS taxes and other charges and insurance. As it turns out they charged me an additional $40 per day for a upgaded car on top of the qriginal charge of $27 per day I selected then all of your charges are increased by the increased charge. NEVER AGAIN WILL I USE THRIFTY NOR EXPEDIA!