Best practice for Anonymous Donation forms?

Donation forms are meant to be easy to use. Easy enough to use implies that it may convert the casual website visitor into a donor. We are currently using the fields:

Card Type Card Number Card Expiry Name on Card CCV Number $ Amount

...and it appears to be working. The issue now is that our payment gateway is being used for fraudelent activities. (A discussion for another forum - our payment gateway is being used for a whole lot of $1 payments against a pattern of "Name on Card" and "Card Number" attempts. Of course the baddy behind the operation will see a "Thank You for your payment" page and then record that against a working credit card).

We are dealing with issues re: charge backs and raising the minimum donation amount to $2. But I don't think that's going to solve the issue.

Other thoughts are to:

  • introduce a Captcha field
  • introduce a mandatory: street address and/or phone number field

...but I am not sure whether they'll eradicate the problem. Furthermore, it may deter the authentic donors.

What are your thoughts?