The large payment security fee appears to simply be a ploy to work around the fact that VISA's rules only permit flat fee convenience charges (with an exception for tax payments).

See this document:

http://usa.visa.com/download/merchan...tions-main.pdf

...and search for rule: 5.2.E

As I read the rule they wouldn't be permitted to charge any fee: The requirement for an alternate payment channel means that Mail/Telephone Order and Electronic Commerce Merchants whose payment channels are exclusively non-face-to-face may not impose a Convenience Fee., but that's probably been discussed elsewhere.