It just don't work. After few day's your money transfer to your bank account and your seafight account is banned until you pay all the item's you earlier bought.
Let me show you a pic how it will look (In this case I used paypal and paypal was using my credit card)
Edit:
If it's working for you, keep using it but I don't recommend new people to try that if they are not ready to take that risk they will lose that money and getting a account ban.