Hi! I have bought business class tickets (LHR-LAX-LHR) and am trying to upgrade them to First using Avios. Under ba.com's "Manage my booking" there is an option to upgrade, but it always says that this booking can't be changed, and advises to call Avios helpdesk. I called Avios helpdesk and they said that this is normal. They said that I could go to "Spending Avios" -> "Explore and check availability", make sure that the "From" field says "London", select LAX from the map and go to the month my flight is due. If there is availability to buy economy ticket with points, there should be also availability to upgrade business -> first using Avios. Does anyone have experience if this advise is correct? Also, are there any other ways of upgrading my tickets, preferrably with Avios?