Update
Thanks for the continued advice here.
I have spent many hours on the phone to Expedia and escalated to a supervisor who in turn tried twice to resolve the issue with BA.
Unsurprisingly we got nowhere.
The explanation from Expedia (having corrected the first call handler four times that the flight was 0230 and not 1430 today - they kept trying to claim this was the reason Qatar cancelled it saying the PAX missed the flight this afternoon!!) and BA is that they deny the flight was overbooked (then why would the check in staff tell the PAX this before anything else?) and they are maintaining it was a fraud check on the payment and that it was Qatar who cancelled the ticket. (I don’t get this because the PAX confirmed the payment address in the card which is all they asked for at the airport).
It appears that Qatar wanted BA to email them (Qatar) to confirm the ticket was legitimate but BA didn’t do so.
Again this doesn’t really make sense. The fact that we had been on the phone to BA and they assured us there were no issues with the ticket or payment, means someone is not giving the correct advice.
Expedia say there is nothing they can do as BA have already instigated the refund procedure.
Result is that we have two PAX now stranded for two days in the airport and have had to book with a different airline for a more expensive flight.
No one is taking any responsibility. There was no fraud, they have not found any evidence of fraud and yet the PAX were still refused the flight.
We genuinely don’t understand as their explanations are not making sense.
To clarify one of the questions someone raised above, Expedia were adamant there was a BA help desk in the airport stating they were on the phone to BA as we spoke and BA were confirming there was. Again this raises further doubts that Expedia really were on the phone to BA, or were BA themselves providing false information?