I ran into problems trying to use my Bank One BA Visa on the Internet to purchase from BA's web page (to get the 2 miles per dollar). When I called to complain they said that they've had so many problems with online charges that they now automatically decline them unless the customer calls. Perhaps your problem is something similar? It does seem a bit stupid that they would have a problem with online charges but allow charges abroad with no problem, so might this be a potential reason? (It might also explain what wanaflyforless experienced.)