BEWARE CAR RENTALS!!...Duplicate Charges with Car Rental through AARP

We booked a rental car for 25 days through AARP, thrilled at the savings we incurred. We were charged when we booked by AARP. When we got to the rental counter at Logan Airport, the rental agent was confused that we had booked with AARP, and then saw that they use a third party, mentioning Priceline. We were sent to Enterprise for the rental, which was also a nice surprise, having used them exclusively in the past but had to make a change when their costs went sky-high.

Fast forward a month and my credit card statement now shows a duplicate charge for the rental by Priceline. I don’t have any activity on my Priceline account. Calling the number ON the statement for the charge gets me nowhere as their agents can’t find my rental either. Enterprise can’t do anything because they only show that they charged me for tolls. Which loops me back to AARP, and I am unable to get in touch with a person to help me with this.

We booked with AARP. The initiated everything from that point and it is their responsibility to correct this duplicate charge. But, there is no help anywhere to be found. 

Any insight, advice, or others who’ve been through this and had success in getting the duplicate charge refunded?