I'm trying to use my brother in law's miles to upgrade a flight for myself (with his permission).

He logs on, selects my name and booking number and goes all the way through to payment (extra taxes ex-UK). At the payment stage it asks for billing information and we want to use my credit card. There is a box here pre-selected which says "Please use my Skywards information" and it won't let me untick it.

I can manually enter all my cc details and go on to confirm the booking but it is getting rejected with the message "Sorry we are unable to process your online payment". It is not getting as far as my bank as I've called them to see if the issue was at their end.

Has anyone else come across this or managed to do what I'm trying? Is there any way round this or do we have to call Skywards?