Well, the only way to avoid credit card problems is don't use them. I've had $1,000 fraudulent charges to mine after returning from Mexico twice. My bank called me immediately, stopped the charges, no losses - just had to replace the card. These can happen anywhere tho. Forging your signature to an inflated charge is different, but can happen anywhere. You dispute it, even if it takes some time. My credit card sig is a D followed by chicken scratch; maybe I should use a legible one? Well, I would on a car contract.
Thanks for sharing the story on a new one to watch for.
Don't know about Mexico, but in the US you can't rent a car without a credit card.