WFT, how does your company travel purchase policy work?
At mine we have a personal corporate card linked to Egenicia. When I make the initial booking, that is the receipt I use to claim against my corporate CC. I haven't done an upgrade yet, but I have paid for seat allocation and just did that on my own credit card (linked to my BA account). The company doesn't see anything other than the original transaction, anything after that and on my card is fine.