Priceline Name Your Own Price, Car Rental Norwalk Connecticut

I reserved a flight, hotel, and car via Priceline, then needed to change the date.  The hotel was no problem,I had to pay a change fee with the airline (which I would have had to anyway), but both Hertz and Priceline told the car rental was non-changeable, due to 'Name Your Own Price'.  I did not use the Name Your Own Price option, but selected from a list of prices shown me.  There was no indication of non-cancellable status ountil after I confirmed.  I consider this practice deceptive. - I don;t see how I could have been considered as using a bid system when I made no bid, but only selected from offered prices.  I called customer service, but they were no help, and only gave me a snail mail address for further escalation, so it looks like they're stonewalling.