I rented a car in Iceland from Avis and cracked the bumper. At turn in, I told the rep about the crack and he said the cost would be ~1,500USD. Since I was in a hurry to get to my plane, I signed a form accepting responsibility and paid for the damage on the spot. That said, I thought the charge was quite out of line with the extent of the damage and told the rep that. The rep said that it might be possible it would end up being less than the estimate, and in that case I would be refunded the difference.

When I got to my next destination I called AMEX (I have the gold Delta Skymiles card, which I've had for about a decade now) and they suggested disputing the charge so that AMEX can have leverage to get AVIS to cooperate with them. The rep said that it is often the case that rental car companies will not bother cooperating with AMEX if they have already been paid in full for the damage, so it is standard policy to dispute the charge until they have what they need from the rental company.

However, when I picked up the car they told me that I would have to pay a deposit on it to the tune of around 500USD. I never saw that charge posted at all. I also have not see the charge for the cost of the car be posted yet.

How should I proceed? Should I dispute the damage charge? If they post the deposit charge should I then also dispute that? Obviously I would not dispute the charge for the rental of the car itself.

Does anyone have experience with this?