Apologies for resurrecting this thread. I have the same issue. I booked 3 outbound flights last week on the stroke of midnight using the 2-4-1 companion voucher. This morning, a week later, I attempted to add 3 inbound flights to that booking but couldn't get though via telephone. I eventually booked the 2 last available avios seats and called BA pre 7am this morning to have the 2-4-1 voucher applied as well as booking a 3rd inbound flight for my son. The guy I spoke to on the phone couldn't find availability on the flight (yet I was able to via the app) He could only merge the bookings rather than applying the voucher to the inbound flights. And this took almost an hour to get precisely nowhere. Am I missing something? I've tried telephoning before 9am but was put on hold. Any advice would be gratefully received. Thanks in advance!