Can anyone help me to get a refund from BA for exit extra leg room seats I paid for £605 but didn't receive?

On both legs of our flight to Orlando the plane was changed and we were put in normal economy seats behind the exit row. We had no choice – the new seats were allocated to us on arrival at the airport and the plane was full so there was no possibility of being able to upgrade.

I made 5 applications on the BA website and all now say they have been closed but I have not received any explanation. I have not received ANY emails. I checked the email address they have which is correct.
I have spent above 15 hours on this so far - on BA customer service chat and on the phone to BA but no-one can help me. They just say it’s with Customer Services. But Customer Services can't be contacted by telephone and are not sending me any emails so I have no route to escalate the refund request. It’s just awful they can take your money, not provide what you paid for and not give a refund. I am completely at the end of my wits and am about to issue a claim in the small claims court out of complete desperation. The refund is genuine and legitimate. We paid £605 for 3 exit row seats there and back which added a an extra third to the cost of the flights. The staff on the plane completed a refund request and said we would be refunded within days (which we obviously weren't) so I didn't keep boarding passes or take photos of the seats. I didn't expect this kind of battle with BA.

If there is anyone out there that can help - please respond.