Can't seem to easily find an answer for this, but how long after a rental is completed does Avis have to bill me for damages? I had a one way rental LIS-AGP after a flight cancellation where we needed to get to AGP overnight in order to make our onward connection back to the states. Since there were no flight options that would get us there in time we ended up having to do a one way rental and drive all night in order to make our flight. The Avis station at AGP was closed when we arrived so we left the keys in the keydrop and the car in one of the designated return spots.

A few hours after returning I received a final receipt as well as an invoice for approximately 3000 Euros in "damage" to the exterior of the car. We had marked up the inspection form for preexisting damange with the LIS Avis agent and from what I can tell (the invoice text is all in Spanish), it looks like they're charging us for the preexisting scuffs and scrapes we marked on our inspection form. I already called Avis US customer service to dispute the charge and emailed them the copy of the signed and marked up inspection form, but I want to make sure that there aren't any other phantom charges coming my way before I file a claim with Chase. They charged my credit card immediately for the full amount of 3300 Euros/$3900 (rental fee + damages), and that charge has posted, but it looks like there's still another pending charge from the same day for a similar amount of around $3800. Not sure if this was just their test charge that hasn't dropped off yet or if they really intend to bill me another $3800 on top of the original $3900.

That said, is there a chance there will be additional charges headed my way or is the initial invoice supposed to be comprehensive? If there is a chance there might be more charges, how long after rental return does Avis have to inform me? And on a separate note, how long do these types of disputes generally take to get resolved after initiating with US customer service?

Until you speak with the agency at AGP you have no idea whether this is pre-existing or new damage. Perhaps somebody hit the vehicle between drop off and the opening? I would get the details down clearly, using someone who speaks fluent Spanish on the line, before making other calls. You are simply inviting a bad result if you do not. That will also get you to understanding whether there are two charges or one and whether that is the end of it.

Claims sometimes take months, so no, what you have may or may not be the end of it.

Once you have full information, you can then deal with Avis, your insurance company and perhaps Chase.