After spending a small fortune (nearly $2000) on a month's car rental from Dollar/Thrifty (they are together) at DIA, it was apparent that all they want is the money and clearly aren't interested in service. 

I was travelling from the UK with 4 children - firstly they wanted to push the 'extra special' insurance' which our ebookers pre pay said not to take out. Pushed toll road pass which I didn't need.  Wouldn't help (I had to pay for a tire to get me back to exchange car at the rental - because I didn't take out the special insurance!) "you can put on the spare."  It was one of those little donut ones! not safe for 100miles of highway driving! 

Workers took my son's ipod that he left in car (we returned within 2hrs)! NO ONE RETURNS CALLS! ONLY AUTOMATED PHONE MESSAGES! I wouldn't hold my breath in a real emergency!