Q: I rented a minivan for 37 days with Avis for $1,770. My pickup and dropoff were at the Holiday Inn in Peabody, Mass. The Avis shop was closed when I dropped the van off on a Sunday. I followed the instructions on the door and left the keys with the hotel clerk. I parked the van in front of the Avis door.

I expected a receipt via e-mail, but none came. Avis then charged me two times — once for $1,459 and then again a few days later for $1,125. I could not get through the Avis phone jungle to find out what was going on, so I had my credit card block the second payment.

Since then, I have been going back and forth with Avis, answering repetitive questions and providing copies of my reservations. I would like to get a revised invoice for $1,770 and have Avis cancel the second charge, then bill me for the remainder owed. Can you help me?

A: Avis should have billed you for the correct amount the first time. Once you pointed out the error, it should have quickly reviewed its records and adjusted your bill. But it didn't.

I reviewed the correspondence, and you're right. The company keeps asking you the same questions, to which it already knows the answers. It feels like you are dealing with a bot (and maybe you are).

Here's my best guess: You returned your van on time, but Avis didn't mark it as returned in its system. So it charged you for the extra days until it found the vehicle. That often happens with car rental companies. It's one reason I advise people to always return their vehicle when the rental location is open so they can get a receipt. Leaving the keys with a hotel clerk isn't enough, no matter what the rental company says. But you couldn't have known that.

Blocking the second charge on your bill fixed your problem in the short term. But if you had refused to pay, Avis could have referred you to a collection agency or added you to its "Do Not Rent List." That would have affected your credit and your ability to rent cars in the future.

I noticed that, after a while, you began writing in all uppercase letters (that's considered shouting) and threatened that they would hear from your legal counsel. These tactics are understandable, but not always helpful in resolving your case.

I contacted Avis on your behalf. A representative reviewed your invoices and adjusted the amount as you had requested.

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