Priceline and Ace Rent a Car review: Double charged for rental car

On April 7th I purchased a rental car and hotel through Priceline and was charged $617.21 for 4 days use of a rental car from Ace Rental in Colorado. My Priceline trip # was [protected].
On June 3rd I arrived in Denver and went to the Ace Rental car counter. I presented the Priceline trip information. I was told all was good, but they did not have the car I asked for (a van). So they had me fill out paperwork and instead of a mini van I was given a dodge durango - I told them it was not preferable, but I would make due. They had me sign a bunch of stuff and I took the car and continued my trip.
The following month I notice a charge from Ace rental car for on June 3rd for $787.38. On June 7th I was credited back $200.00 from Ace rental car.
On July 2nd I noticed I was double charged and called Priceline at [protected] and informed Wayne with Priceline of the double charge. He took my information and said he would resolve this within 10 work days.
On [protected] I called Priceline back and spoke with Vam. Vam looked up the information and informed me the charges were justified by the per Ace rental. I asked to speak with a supervisor. I was connected with Rye from Priceline and reexplained the situation. Again she stated that their "partner" (I assume Ace rental car) justified the extra $587.38. I asked if I could receive Ace rental cars justification for the overcharge. Rye told me they do not share that information. Being unsatisfied with this answer I asked to speak with her supervisor.
I waited for over an hour and then called Priceline back and asked to speak with customer service. It seems the more I call and identify myself and the trip # the longer I am on hold.
I will continue to try and reason with these folks, but this is really bad business.