Thanks all.

Apologies for the lack of information - the flight was booked via BA over the phone as I had issues completing the booking online. It took almost 3 weeks for them to debit my credit card and, despite asking several times, I did not receive any email confirmation or receipt. This concerned me and I posted on here and was helpfully directed to " heck my trip" where I could see the booking reference (which begins 125).

The online claim form does not accept the ticket number (either mine of my husbands) and whilst I still have the boarding passes the ticket number does not appear on them either.

I think I will try the general contact form. The phone calls simply aren't getting me anywhere, the agent immediately claims the ticket number does not exist
and therefore there is nothing they can do to help.
It's all very confusing - not helped by the last agent who suggested that we may not be allowed to board the return flight as the ticket number doesn't exist!