The paid M&Gs I've been to have basically been roll calls of names, I don't ever remember needing the card they were paid for on (which is a good job, as they've usually combusted by then!)
Wondering if there's a way just to change the name on the M&G as if it was a gift, which you should be able to do as you've got all of the original payment details...?
(So sorry you might not make it by the way
)