Dollar Rent-A-Car Overcharging by deception Los Angeles California

I had a fully inclusive "premium" pre-pad package with the travel Company (Virgin, UK). It included unlimited mileage, full car insurance, child seat and the top of the range car that I could book from the UK (an 8 seater delux minivan).

I wanted a slightly different model (SUV) that was still 7/8 seats, but could not pre-book that model in the UK. I emailed Dollar before we set off, who said no problem, we have these but you will have to arrange it at the airport. They would not give me a price for the upgrade.
We arrived at the airport after the usual 24+ hours without sleep. I asked if they had one of the SUV's that i wanted, as the seating arrangement is better for us. They had one in every color- no problem. How much would it be to upgrade this (already top of the range model 8 seater van) to the SUV? Special offer for me, "$50"- it would normally be more, she said. Sounded fine. I was given the form to sign and Emily was very good at holding her finger over the boxes. We checked the car as best we could for damage in the dark car park and drove away.
When I returned the car, 17 days later, I discovered that they were charging me for $50 extra *per day*! The form shows this, but I took her word for the extra, and was too tired and confused to follow the form. They had my credit card details, so I was not able to stop the charge.
Virgin in the UK refuse to tell me what my top of their range voucher was worth, so I have no way to see what a fair charge should be.

When I complained on the car return, on seeing the outrageous charge, they looked embarrassed, and said it was a different branch- the policy is they charge more sometimes when they have a shortage (supply and demand) but of course there was no shortage of the model as they could offer it to me in every color.

Fraser
Rattlesden, California
United Kingdom