Unjustified damage fees and fraudulent charges for a rented car. What to do?

Dear Sir/Madam,

I visited Dubai two weeks ago on a business trip, during which we hired a car.

When we returned the car, they said there was damage to one of the rings on the wheel and demanded that we pay 7000 AED without providing a repair quote.

We immediately disputed this but paid for all extra mileage, tolls, and a speeding fine.

We disputed the damage because we did not believe we had caused it. We also took pictures of the car and consulted Mercedes UK for advice on what should be replaced, if anything.

They advised that it was minimal and would cost at most 200 AED to repair. I offered to pay this as well. Since returning to the UK, I have been receiving daily messages threatening me with police action and arrest upon my return to Dubai if we do not pay the money.

We paid a 2000 AED deposit on a credit card, which they advised is released. I have written confirmation of this. However, my card has now been charged 2300 AED without my authorization, which is likely fraudulent.