Not with BA, but my case was ripped after an ADD-LHR-BHD flight with BMI. I was given a reference number and a number to call. The agents asked me the make, age and cost of the case. My case was a Travelpro, but I did get it for a great price, sub £100 if I recall correctly. At first they refused to replace it with another Travelpro (or similar) case, because I had paid a low price for it. They wanted to give me a Skyflite case which they reckoned was similar in cost to what I had paid.
My argument was that what I had paid was not relevant, I should have a replacement of the same standard as the one which was damaged. After a number of calls over two or three days they agreed to replace with a Travelpro.