Attempted.
Unfortunately the site authenticates the donation using a "verified by visa" protocol (in my case) run by mycardsecure.
Get the password wrong just once, it invalidates further transactions.
Unable. I'll try again after the bank opens tomorrow.
Might be worth mentioning to the charity that although this is a fairly good security check, it's damn cumbersome. I can't use a different credit card, such as Amex.
All the best.