The problem may be behind the scenes - meaning there's nothing wrong with your clients card. If your client has used her card multiple times in the past with PayPal and has always paid as a guest (no PayPal Account), it's quite possible that PayPal is hinting, she needs to open a PayPal Account.
Here's the possible theory:
Your customer has probably exceeded their limits using their card to check out as a guest, if they have spent approximately $4000 or has used their card 15 times as a guest, they will not be able to pay with the same credit card unless they create a PayPal account. Their only options at this point would be to either create a PayPal account or use a different credit card. It would appear that PayPal may have flagged that particular card.
What's your possible work around for situations such as this - switch to Payments Pro.
With PayPal's Payments Standard, PayPal advertises that you do not have to have a PayPal Account to make a purchase. This statement is quite true however, there is one small bit of very important information that is not mentioned in any of the available documentation. PayPal's mission it to sign up new business or accounts and by tracking the number of times a credit card is used is one method designed to help accomplish that goal. Opening a PayPal Account may be OK with some of your customers or clients but, perhaps not all. Just something to be aware of.
Payments Standard is great concept because you pay only for the services you use but, there are some limitations as this is one of them. For folks who really just want their customers or clients to pay with a credit card with no limitations as described above, then the product to use is Payments Pro. Pro is different as it does have a monthly fee, plus transaction fees and there are specific PCI security requirements to consider.
