I am expecting a large refund from Amazon which obviously they have on my old card no. from before the payment processor issues.
What problem is this going to cause with my refund which they have promised in the next 5 to 7 days?
Welcome to the community @iannorman82 !
Best to follow this thread for updates regarding refunds: Wirecard: Refunds
Regarding the refund coming to an old card - Curve processes refunds at an account level (which is unique to every customer) regardless of the card number, so your refund will arrive safely.
Since your refund has yet to come, its likely it may arrive on Curve Cash based on the current progress (see thread above)