Q: I rented a car from Avis and dropped it off at Tweed New Haven Airport after driving up from Washington, D.C. The Avis counter was closed, so I called them and did the rental handoff over the phone. A representative asked me for the number on the key. I asked if he needed anything else from me, and he said no.

I did not hear anything back from Avis for a few days, so I followed up. Once again, a representative assured me that Avis had closed my reservation. I later learned that Avis closed my rental more than a month after I returned my car. Avis has charged me $4,228 because it claims I kept the car for 34 days.

But that's impossible. I moved to Germany two weeks after renting the car. Also, the odometer from the rental closure invoice reads as if the vehicle has been sitting in the New Haven airport rental car lot this entire time.

I have submitted gas receipts showing I filled the tank in New Haven before returning the car. But the evidence doesn't seem to be enough for Avis. Can you help me?

A: Avis should have closed your rental as promised and not charged you an extra $4,228. But you returned your vehicle after hours, and unfortunately, that's asking for trouble. I've had many cases where cars go missing or are mysteriously damaged after hours. In almost every one of those cases, the car rental company assumes their customers are at fault, and charges them for it.

Your problem was no different. It looks like you did everything you could to return your vehicle on time. You made multiple calls to Avis. You checked on the return. And still, it charged you for another month. If you're living overseas — and can prove it — then how can Avis continue to insist that you were driving one of its cars?

The only surefire way of keeping this from happening is to return your car during normal hours. Then you'll get a receipt, which is written proof that the company closed your rental. If you have to return the car after hours, ask a representative to e-mail you the relevant documents. And if you can't do that, then record the phone conversation (where legal) and note the name and extension of the representative.

I reached out to Avis on your behalf. It investigated and found that you did not park the car in the Avis lot when you returned it. Avis eventually found the vehicle and closed the contract. You received a full refund.

Christopher Elliott is the founder of Elliott Advocacy, a nonprofit consumer organization. Contact him at elliott.org/help or chris@elliott.org.