I read a post the other day about using a credit card to purchase points and security issues because the normal security features do not show up on the screen. I wish I could find it because I would have put this in that thread.
I am going to purchase points in the near future. And when I do I am going to a local store and put money on a card that I use a lot on the internet. I got the card at a local market and you can put money on it as you need it so I will get however much I decide, probably $15.00-$25.00. I will use that card to get my points.
If anything goes wrong, which given WGT reputation I do not believe would, your risk will be minimized and you can have more piece of mind. But I use this as a extra security measure so no one can get the number and run up charges.
If you have any issues with using your credit card, it would be my suggestion that you try this.