Re The single points of failure?
Probable senario:
About 5 years ago they set up a load balanced system where each data centre handled 50% of peak load with a few spare boxes.
About 3 years ago they upgraded some servers to handle extra load but did not bother upgrading the spare capacity.
About 2 years ago IT pointed out that with increased traffic each data centre could now handle only 70% of peak load but 50% of normal load and management decided that was "good enough" as peak load only occurred 5 or 6 days a year.
About a year ago everything outsourced to India, nobody noticed (or were too embarrassed to point out) that each data centre now only coped with 80% peak load.
Yesterday one data centre crashed. The remaining data centre tried to cope with 160% of peak load, chaos theory was invoked and the systems crashed one by one, and, crashed again on restart.
When power was restored at the other data centre the databases, queues etc. were in a state that required experienced engineers with deep knowledge of the systems involved -- like the ones that were handed there P.45 last year.
Not sure how much this will cost BA -- but just the 200 to 400 euros due to each and every passenger should be enough to have the shareholders demanding cruel and unusual punishment.