Question by Avangate

Today from one of the American clients I received a letter with the following content:

I purchased your AMEX business credit card. I was going to make a purchase online. I called AMEX and they seemed to be locked in an account. My account. You might want to consider a different card processor ...

A question for the rest of the sharovarshchik: does Avangate really have a bad reputation in America, or is such a blocking an isolated case?