Ambassador, British Airways Executive Club, easyJet and Ryanair
Join Date: Sep 2011
Location: UK/Las Vegas
Programs: BA Gold (GGL/CCR)
Posts: 15,913
What type of upgrade is it that you are trying to make? If it is a 'Special Offer' upgrade (what we term a 'POUG') that you have seen in MMB then that should be possible. It is is an Avios upgrade, then yes there is a way around that (subject to P class availability). If you are just trying to buy a 'fare difference' upgrade then this is not normally possible.
The best way to find out is to call BA and see what they have to say about the possibility and the cost.