Oh Hertz how I hate thee (part two).

I've been trying to modify some bookings recently (yeah I know stupid me).

When I go to confirm the update, the site now requires another credit card validation .... but rejects the updates during the process as invalid CVV number for booking ... what is happening is that the box that you need to put the CVV into isn't appearing ... so to update a booking I need to change the credit card and that will allow the CVV to be entered... Okay I have two credit cards, no problem, but only one is Zero FX and these are US bookings I'm trying update, so I have to cycle the credit cards in and out of the booking.