Thrifty overbooked their rental cars

Thrifty overbooked their rental cars, which caused we waited more 2 hours. The staff solicited me to raise cost to upgrade car & get car soon, otherwise there will be 2 more hours waiting. I provided my phone number to get their notice. After 2 hours waiting by the counter, they did not inform me the car was ready until I approached asked the staff, then he said my car was ready....