An update. I submitted a complaint through BA's website on 22nd July. A claim reference number was generated although the automatic acknowledgement e-mail at the time of submission was not sent.

I've heard nothing further and when tracking the status of the complaint it is shown as being in the queue with the ususl disclaimer that BA are working through a huge volume of cases (no comment).

Are there any views on how long I might expect to wait for a response or alternatively what the best route to escalate is given their failure to respond?

Thanks