I've recently voiced a gripe of a past experience in the BA thread.
Having a nice day out in Luxembourg, and due to return on BA City flyer Express to LGW (I lived and worked at LGW so I didn't want to travel to any other LON airport) the next day, BA telephoned me to tell me that my next day's flight LUX/LGW was cancelled due to aircraft technical.
Having then been an Operation Officer, Operations Controller, Crew Scheduling Manager etc. for some 20 years I laughed at the guy to the effect "So you're telling me that in BA's entire fleet they don't have a spare aircraft of any description to operate LUX/LGW tomorrow?" and he told me that was the case.
I then asked him if they had tried sub-chartering in an aircraft to operate the service, I knew he was BS'ing me so I told him to "give me 30 minutes, I'll find an aircraft for you, I've been doing it for the past 20 years" ... I can't recall his words but I realised that I wasn't going to achieve anything by arguing.
BA involuntary rerouted me on a LuxAir B737 via LHR and the aircraft was so empty it was embarrassing, "cancelled due technical" my @ss!
So they should be sued.