Rentalcars.com Double charge scam. Liars, thieves and cheats. Internet

Booked with rentalcars.com a 12 day 2-stop car hire from Miami airport in march/April 2013. 

i was assigned a car from budget. i purposefully chose a tank of petrol to be included as well as fully comp insurance to make sure no hidden charges. 

in Miami at budget desk was informed that my car wold only be released to me on signature of agreement full of supposedly optional extras. When instated I did not want or require them was told that I had to sign form or would not be allowed to take car. It was 11pm after 14 hours travelling with 2 young kids. I only signed the collision damage waiver section and left the rest blank. Assistant promised that I wouldn't be charged extra but stated she could only print out the same form again as this is what was in system. 

on return checked credit card bill to see I had been charged £220 by budget. 

Clearly I had been scammed by the assistant looking for commission. 

Complined to rentalcars.com who promised to look into it. Received reply 3 weeks later with PDF scan showing the form I had signed in 1 particular place and left blank in others. It now had a new signature added as well that was not mine. Rentacars rep agreed and said would approach budget. Was promised a call back that never materialised. When I was eventually called back by Antoine he said there was nothing he could as they said I agreed to it. 

He refused to believe me despite evidence of fraud and forgery. 

i believe that rentalcars have a responsibility to me as their customer and that they are a disgusting organisation who wouldn't know customer service if it hit them in face.