Dollar Rent A Car double billed, hidden charges Internet

I rented a car through Dollar Rent a Car.  I picked up the car in Tampa, Florida and made arrangements to drop off the car in Fort Lauderdale.  When I looked at my bank statement, I noticed that Dollar had double billed me.  I originally prepaid the rental back in March for $270.  When I got to Tampa to pick up the car, I had to pay an additional $305.00 for insurance ($36.99 a day) numerous charges such as "CONFEERECCHG" ($35.61), state tax, a prepaid "PASS 24" to go through tolls on the ez pass, Florida surcharge, and energy recovery fee.  The mileage was listed as unlimited.

When I called Dollar to explain why they had charged me $305, and $407.42, they could not itemize or explain this.  The only thing I was told was there was an "adjustment" to my final bill because I did not drop off the car at the correct location.  Apparently they had me listed as having to drop off the car at an off-airport site in Fort Lauderdale and I dropped the car off at Fort Lauderdale airport instead.  So I had to be charged an extra $97 for this. 

Even with this explanation, it does not explain why there are two charges.  One of the charges should be a credit and one should be a debit.

This company has ripped me off big time and double billed me.