Here is an option that works very well for me so I don't have to worry about it every month....
1) I created a PayPal account which is free to join...
2) Apply for a Credit /Debt Card...
3) Set-up through SFI to use that account to be charged...
4) Once your account is set-up you can fund it or pay towards your balance every month...
5) Gives you the flexibility to pay for auctions or items you purchased or won at SFI...