Booked a car via Avis from BA Holidays.

Had to swap the car mid hire.

However Avis has charged by Amex for around £900 for the car hire upon drop off.

Any suggestions on getting this sorted?

My contract is with BAH, I guess so any suggestions on who to contact etc.? Email address for example?

On the ticket email there is a link for further assistance but that link is a 404 so not too helpful.

I am guessing that this is not a matter for the Gold desk.