How do I Contact the "Bill Me Later" Customer Service?

I received an email from Bill Me Later indicating there was a problem with my account and I could not use the Bill Me Later Service. They did not provide a customer service number or email to contact them regarding this matter. How am I suppose to get in touch with them for find out which purchase they are referring to and what the problem is with the account. I have several email accounts and I do not remember when I signed up it the account was in my name or my husbands. I believe that one of these is the problem as to why I could not use the Bill Me Later but it has been a week and I have not heard form any companies indicating Bill Me Later denied payment. Is anyone familiar with how this works and who I can contact for Customer Service. You could not hit the reply button to get them and I do not have an email or address to contact them. Any suggestions?