Good thing you cancelled the reservation:

"If a flight has been cancelled by the airline, it is necessary for you to call the Customer Service Contact Center at 1-800-352-7900 option 5 (other), then option 4 (billing), prior to your scheduled arrival time to avoid both the $25 Cancellation fee and the $100 No Show fee. "

http://www.avis.com/car-rental/conte...navId=T4M28S07

https://www.theflightexpert.com/avis-pay-now-discount/