Is there a way to trick samsung apps to thinking you have a real credit card?

I bought a new smart tv from Samsung and wanted to see if there was an app I wanted to buy. So, I looked and found one. When I did it asked me for a credit card number so I gave it to them. Now though that I added my card online I can not remove it. I called 1800-Samsung and they can't do **** I contacted the live support and webmaster(But webmaster never replied back) So my only option is to use a valid fake card number. The site I'm talking about is here : http://www.samsung.com/us/appstore Once you enter your card you can NOT REMOVE it only change it. SO, please someone be able to help me out, thank you and merry Christmas and happy new years!