Poor service marred otherwise excellent service

As a regular user of the Avis chauffeur service I have made bookings for transfers in June and July under reference - Case: l6pMZs, Reference: JjDIGq]. Due to health issues I had to change the transfers to alternative dates. Avis has however reserved the fees for the transfers against my bank account and despite numerous requests to release the funds back to my account, no action is forthcoming, marring an otherwise excellent experience with this service.