Andrew, I had a somewhat similar experience with Iberia in June on a flight booked through American Airlines. After being ignored for months, I worked through the AA Plat desk to get contact with Iberia. Iberia, after receiving correspondence (probably email) from AA Platinum Desk, were receptive to receiving my complaint. However, it has been about 30 days since they acknowledged receipt, yet I've heard nothing. My suggestion is if you carry elite status with an airline that is part of the OW alliance (BA for you perhaps?), perhaps you should consider going through their desk.

Good luck!