Budget Bait and Switch St. Louis, Missouri

Booked car through Priceline.com...no problem there.  After paying for the mid-size car online, I found out the car was from Budget.  Standing in line at Budget to rent the car, I heard the customer at the counter in front of me say, "So you are out of mid-size cars?"  I got up to the counter and the clerk told me he was going to "upgrade" me to a full-size car.  I thought he was doing something nice for me.  (In fact, I told members of my family that I got a free upgrade, from mid-size to full-size, because they were out of mid-size cars).  He never told me he was charging me more money for it. 

The day I returned the car, the guy out in the lot who checked me in handed me a receipt for $47.xx that had been added to my charge card.  I asked him what the charge was for and he told me it was for the upgrade.  When I went inside to inquire, I was told, "You signed for it."  Yes, I did sign for it, but the clerk who "upgraded" me on the day I rented the car NEVER told me I was going to be paying more money.  I was under the impression that since they were out of mid-size cars, I was simply being upgraded because there was nothing else to offer me.  I would never have agreed to an upgrade if I would have known I would be charged an additional almost $50 for a car.  I would have insisted on the mid-size car and likely would have ended up with a full-size anyway because of them being out of what I rented and paid for in the first place. 

As I was storming out of the building after my inquiry, the female clerk said, "Have a nice day."  I told her to go to h*ll.