Just recieved this in email. It's been 3/4weeks now.
Intersting this is for a trip ex-eu rather than ex-uk. I asked for refunds for both within minutes of each other and the ex-uk one got refunded back to my Amex within a day.
Booking reference: XXXXX
Dear Customer,
We’re so sorry you haven’t yet received your refund from us.
A system issue affecting a small number of customers has been found that was causing a delay in processing your refund. However, we are aware of it, we have now corrected the issue and are using extra resource to prioritise your booking to ensure you are refunded as quickly as possible.
We understand this is not the service you would expect from us and we thank you for your patience while we process your refund. We will be in touch again once it has been processed to confirm the money has been returned to you.
British Airways