[N.C. Gun Dealer]

This is my first post here so please be gentle. By the way I am really enjoying reading the posts here and have started getting better mileage( went from 29 mpg to 34 mpg) with my 03 Chevy Cavalier with no mods except the way I'm driving. I wanted to hook up an Ultimategauge before I started changing things to get some base readings but I can't seem to get their website to take either of my credit cards(amex or visa). I know the cards are good, they work everywhere else but I tried Sunday and again today,Wed. and they continue to give me this message: "The card you entered cannot be used for this payment. Please enter a different credit or debit card number". I sent them an email Sunday but have had no reply except they received it and there is no phone number. Anybody else had a problem?? Thank, Ricci.