Q: A few years ago while I was on a business trip to San Antonio, National Car Rental invited me to join its Emerald Club at no charge. When I got to the portion of the application that asked for a credit card number, I explained to the agent that I travel on business, but that my company has a corporate account with National. “The actual credit card number can change,” I added.

The agent said that was OK. All I had to do was put my personal credit card information on the application, and when I rent a car, I needed to make sure I give the agent the corporate card number.

I used National’s Emerald Club every other week for two years after that without incident. But on October 20, 2000, my luck ran out when I rented a car in Houston. I gave the agent the corporate card number and went on my way. A few weeks later the credit card I used for the Emerald Club application was compromised and the card issuer closed that account number and issued me a new account.

The next spring, I received a letter from National telling me that the credit card I used in Houston was turned down and that the credit card company had issued a charge back to National. I contacted the account representative who signed the letter and we began working through the details. Eventually we realized that National did not use the corporate card and used the card that I had on file – and since it had been closed, the card issuer did a charge-back.

I contacted my corporate travel agent, who got in touch with National and had the charge put on my company corporate card.

Several weeks later I received another letter from National informing me that it had spoken with the company’s travel department. The correct card had been charged and now there was a new problem. When the corporate card was charged, National’s computer system automatically credited the previously used card. National was asking me to either remit payment myself for that amount or have the credit card company apply credit back to them.

I contacted my credit card company and they had no record of any of the transaction.

I contacted National and explained the details of the entire situation. The customer service representative told me she had spoken with the bank and she could not get them to take care of the situation. Later, National informed me that it was my responsibility to get the money due back to the company.

That fall, I reserved a National car in Florida. When I attempted to actually rent the vehicle, I was told that I was “blacklisted” and it wouldn’t rent to me. I called its corporate headquarters, tried to discuss the problem again, and found the same attitude and unwillingness to work through the problem as I had previously. Can you help me?

– Dave Kifer

A: What a comedy of errors. It looks as if no good deed goes unpunished when you rent a car from National. But what baffles me is that you – a loyal customer – would be “blacklisted” by the company for something you didn’t do.

Almost every travel company keeps blacklists of problem customers who either don’t pay their bills or are difficult to deal with. But you not only paid all of your bills – you were, by your own account, easy to deal with and tried on numerous occasions to clear up this unfortunate misunderstanding.

Before I called my contact at National, I recommended that you give the company one last chance. After all, it shouldn’t take someone in management to figure out how silly this blacklist scenario is.

You phoned National and spoke with another customer service agent who did indeed see things your way. He took one look at your account, noticed the charge-back, and went to work to fix it. Within a few minutes, the representative had cleared up your account. No more blacklist.

I love happy endings like this because you took matters into your own hands and got the results you deserved. It also goes to show that you don’t always need someone like me to be your advocate (OK, so I advised you, but I didn’t make a call on your behalf). And, to National’s credit, it corrected a serious mistake without my involvement. That’s good customer service.

In the future, make sure every company you deal on an ongoing basis has your most current credit-card number. Some automated processing systems will prompt you when your credit-card expires, but they have no way of knowing if the number you gave them is the one they should be using. You’re the only one who knows that.