Q: When I was planning a recent trip to France, I went to the American Express Rewards Web site to look for a rental car. The site directed me to make a reservation with a special code, and then return to the membership rewards site to request the certification. That’s what I did.

Several weeks later, I received the certificate and became very concerned by what I read. The certificate stated: “Valid at any participating U.S. Budget location, unless otherwise specified.”

I immediately called Budget, the car rental company I had made my reservation with. I was reassured by a customer service representative that since the place I was picking up my vehicle was a “corporate” location, that I would have no trouble redeeming my coupon.

The American Express site didn’t say that the Budget certificate wasn’t good outside the United States.

But when we went to pick up the car, Budget refused to honor the certificate. I was forced to leave a $1000 deposit on my American Express Card, and I was terribly upset, because I felt that I had arranged everything just as I had been told to.

Can you help me get the points back that I wasn’t able to use?

– Craig Stewart

A: When you have a question about an award certificate – or really, any kind of question about an upcoming trip – you would expect to get a straight, authoritative answer from a customer service department. But in your case, it appears you didn’t.

It’s difficult to say what went wrong. Maybe Budget’s customer reps weren’t told about the fine print on the certificate. Maybe they made assumptions they shouldn’t have. It’s impossible to know, since I wasn’t there when you called the company.

You probably should have spent more time on the American Express Web site before drawing the conclusions you did. If you click on the site and try to redeem Budget’s car-rental certificates, it warns that the vouchers are “valid at participating U.S. Budget locations only, unless otherwise specified.”

I think that kind of disclosure is good, but when you’re being told the opposite by the car-rental company, why even bother? There’s no excuse for this kind of breakdown in communication – especially when it inconveniences you to the extent that it did.

Next time you use a reward certificate to rent a car (or redeem anything else, for that matter) don’t rely on the reassurances of a customer service agent. Even if you get the name of the agent, it won’t make a difference when you’re overseas and no one is letting your rent a car with your certificate.

If at all possible, get that kind of guarantee in writing. It’s the only way to be sure.

American Express returned the points you didn’t get to use. It also credited you with an additional 15,000 points for the phone cards you had to buy when you found yourself without a car in France. Considering what you had to go through, I think that’s an equitable solution.