Thrifty Car Rental Deceptive and unethical Orlando, Florida

My partner made reservations for a car rental to pick up at Orlando Airport.  Estimate given was about $150, and because we trying to be frugal, we went with them.  When we arrived to pick up the vehicle, the extremely unfriendlt service rep immediately began pressing us to upgrade.  We agreed to a size upgrade because she implied our luggage would not fit (untrue) and told us the upgrade would be free of charge (untrue). 

We agreed to toll charge and extra driver charge.  Fine print contract included many charges we would not have agreed to if each had been explained (i.e., funeral insurance!).  The contract she presented was $470.  When we balked at the discrepancy, she told us "Estimates are just estimates -- they do not guarantee anything."  We decided to sign the contract because of the large line behind us and because I needed to escape the heat & humidity before I passed out. 

When we sat down with our bifocals later and examined the contract we were appalled.  My partner called Customer Service later and our complaint was flatly dismissed because I had signed the contract (I maintain I signed it under considerable duress).  I have never in sixty years experienced such unethical behavior from a company.  The icing on the cake here is that everyone we've spoken to connected to Thrifty has been rude.  What can we do besides warn others of our horrible experience?