Nick and speedbird thanks.
I sent the first fax on 12 Nov and two weeks later on 26 Nov sent an enquiry (with a copy of the letter) asking if my correspondence had been received. One week later on 3 Dec I asked when I might expect a reply.
Perhaps it's a matter of impatience to expect a reply within 3 weeks. I don't know how they normally handle these things having never had occasion to complain about BA's operations before. I suppose it's possible a reply was posted by snail mail from the UK although I requested a response by fax or email.
It was not my intent to make a major issue of this but I thought the circumstances that seriously impacted my business trip were unusual and significant enough (they were to me)that they deserved a reply and that BA, at least as courtesy, would wish to address the matter.