Absolutely! If we do not get a response after several e-mails, we will usually call.
Just to clarify, when we contact the customer, we say that there was a problem with their payment and that it was declined. We ask them to re-submit their information (most of the time it's just transposed numbers or an incorrect expiration date).
[edited by: LifeinAsia at 7:41 pm (utc) on May 4, 2009]