When I started to run low on traveller's cheques in Fort Worth, I called at the local AmEx Travel Services office to try to arrange a cash advance of $200 or $300 on my AmEx gold card. I knew my card account was in good order, and imagined that this would be a simple enough transaction.
But the lady working there said she could not help, as her particular office, "does not have that facility". She explained that there was another AmEx office a few miles away which "might" be able to help, but offered no further information. Then, having been thoroughly unhelpful, she and her colleague suggested that I "have a nice day", at which point I gave up.
I didn't have a car, so getting to the other AmEx office was not a practical proposition, which was just as well as it turned out. I was able to fund the last few days of my holiday by piling as much of my spending as possible on to the AmEx card itself, and using my few remaining dollars only when there was no alternative. But why had AmEx refused to help me out?
Atalia Da Silva, the company's London spokeswoman, says: "US banking regulations don't allow American Express or other non-banking organisations to give cash advances on card accounts. If you need cash, we can always do emergency cheque-cashing, but it's not as convenient."
That wouldn't have been much help in my own case, as I would have needed to have my UK cheque book with me. So, far from explaining the true situation at the time, the AmEx office in Fort Worth had instead directed me to an equally useless office a few miles away.
Ms Da Silva's guess is that the Fort Worth staff didn't understand the banking rules themselves. If I had pressed the matter, they would probably have been able to organise a transfer of funds from my UK bank account, she says.
The upshot is that although I could not get any cash on my AmEx card, using a Visa card or a Mastercard at any one of the nearby banks would have been fine. "Visa is a banking organisation, whereas AmEx is simply a card issuer," Ms Da Silva explains.
Another alternative would have been to use one of my credit cards to withdraw cash from a Fort Worth ATM. This too was impossible in practice, as I never use these cards for cash withdrawals in the UK, and had no idea what the relevant PIN might be. Of course, I can hardly blame the card companies for that.
My trip also produced a hiccup with my traveller's cheques. One bank, this time in Memphis, refused to cash my AmEx cheques because they had an exclusive deal with Visa. This was only a tiny inconvenience, as there was another bank across the street which cashed my AmEx cheques quite happily, but it did make me wonder what might have happen if I'd been holidaying where only one bank was available.
Ms Da Silva says: "There are a couple of US banks that have those exclusive deals, but it's very rare."
A Visa International spokeswoman, Selina Carter, says her organisation has 14,437 member banks in the US, all of which accept Visa cheques. But she cannot say how many of these turn down competitors' cheques.
As it turns out, I could also have used my own bank's cash machine card with my existing UK PIN (which I do know) in both Memphis and Fort Worth, although that option never occurred to me at the time.
My cash machine card has a Cirrus logo on the back, identifying it as part of Mastercard's cash machine operation. Apparently, there are about 200 Cirrus-badged ATMs in the Fort Worth area, so it seems safe to assume that I could have found one within walking distance of my hotel.
Richard Tyson-Davies, of the Association of Payment Clearing Systems, says: "The other logo that you'll find on ATMs around the world is Plus, and that's linked with Visa. These are the creatures of the two international card schemes. You may see machines badged Mastercard and Visa, but you're more likely to see Cirrus and Plus."
The lesson would seem to be that not only should you take more than one means of spending when abroad - cash, cheques and plastic, say - but you may also have to take more than one brand of each. It will also help if, unlike me, you can remember more than just one PIN.
To find a nearby Cirrus machine while in the US, call 1-800-4-CIRRUS. Calls are toll-free. You can reach the same service from the UK by calling 001-800-4-247787, in which case calls are charged at international direct- dial rates