Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,170
Is this a cash ticket or an award ticket?
If cash, just remove your BA number and input it again later. Alternatively, try to select your seat with the IB App or on the RJ website.
If award, your IB+ number is probably a bit sticky and that is overriding your BA number.