Have had problems with this Airline too, with their phone system, been even hung up on through my fustration to get through to the correct departments, no one seems to know their or wants to give out their direct numbers, only only 0845, numbers.
You could try BA baggage tracing (you may already of tried these numbers) 0845 7222767, or for a geographical number (which means the airline does not get a cut on the 0845,0870 telephone fiasco for keeping you on hold) 0191 490 7901. This is a Newcastle number, but they apparently deal with lost mislaid baggage for BA.
Hope this helps
JIPPO