Double charged

On the Apr/9th, I prepaid the rental of a car with a cost of $89. The pick up and deliver was also choose to be different location. When we went to deliver the car (within 24hrs), the Avis was closed (sunday). I called customer service and asked how to proceed (i was on my way to drop off at the airport), and it was instructed by the customer service to leave the car in front of the Avis store, drop the key, the contract and the fuel proof at a designated box. So we did. At the next day I received AN EXTRA CHARGE OF U$147 on my credit card. Called customer service, no resolution. Went to the pick up location, spoke with the manager, he mentioned that the drop off charged us one extra rent, and he emailed them, and still no response. Case T***D More than 3 weeks and not even a response. Reservation number: ***5BR2