Hopper review: Flight

I booked a one way flight from Hanoi to London to take place on 30 April 2026. The flight is run by Qatar/British Airways. Because of the war in the Middle East, British airways offered a full refund which I wish to take up as the flight was through Doha, with a 12 hour layover.
I have NOT been able to get anywhere with the app or the website - the virtual assistant is useless and I cannot call because the only calls accepted are from the USA or Canada - I am in Cambodia at present.
I have sent emails and have received not even an acknowledgement, never mind a coherent reply. I need the money back (not a voucher) as I need to make other arrangements to get home.