I don't think "fickle" is the term I would use for BAs IT. Ramshackle, not joined up, illogical and probably badly programmed and managed feel more like it.
I too got check-in reminders for the flights that had been cancelled, which sent my wife into an apoplectic rage with "insult to injury" being the mildest thing that could be said.
BA have been sliding down a slippery slope for years and the arrogance of thinking that I'll deal with them again, where I have a choice, is staggering.