This could possibly the reason some Mexican companies will not accept your U S credit card. I do some work with Volaris and for several times paying for (freight cargo fees) they would not accept my U S credit card but when I change my address to a Mexican address on my usaa account they they accepted the credit card I had to change my phone number to my Mexican phone number also. This might be the reason for not accepting your U S card but they would accept my debit card before I change my usaa info. I'm going to try my card with the change soon with mercado libre and see what happens phil