I keep hearing about these fairfx cards, but I can't work out if they can be topped up/ re-loaded while you're away. Does anyone know how easy it is to do? I'd like to get one, especially while the $ is so weak, but I'm worried that if I don't put enough on it and I run out of credit I'd be stuck without money. We always like to take too much anyway, but if DW and DD hit the malls I might need to add a bit more.