We are flying from LHR to PHL in November. We have business class/club world seats. Mr S flies with a portable oxygen concentrator, and for that flight he has requested to be hooked up to the airplane oxygen. We have done this before with no issues. For this flight BA is refusing to give him a seat assignment. Of course we want to sit together. Right now I am upstairs in clubworld.

Anyone have a suggestion for how to handle?