I do understand your frustrations - I've been there myself in the "computer says no" scenario, in my own case where my wife and I had taken the exact same flights, but due to BA selecting an arbitrary date for extensions, she got a year extra and I got nothing. It was that lengthy exchange which disabused me of any notions that BAEC was about loyalty, and while I don't always succeed, I do try to take a more transactional approach these days.

As has been said, put in for ORC anyway - there are guides on the forum how to do so. For the effort of filling in a form, you've nothing to lose. You might get the points, which should retroactively retain your Bronze.

I probably didn't explain myself well enough regarding the alternate transport. I appreciate the alternative they gave you was useless. In that case, the advice from BAFT would almost certainly have been, "don't cancel the ticket, take the train, send BA the bill for the train ticket". In that case ORC would have been a formality I suspect.

I completely understand why these things aren't on your mind at the time, and that you were given advice by the call centre to cancel, so why would you doubt it? Before I joined FT, I would assumed everything the call centre told me to be the best option, but the unfortunate reality is that isn't the case. While there are many great agents, there are lots of new ones who are less skilled, and even allowing for that, they are necessarily generalists - they are necessarily not versed in the nuances of BAEC. If there's one bit of advice I try to remember from BAFT, it's never rush to cancel. You can always get your money back later if BA cancel a flight, but once you opt to cancel, it does tend to weaken your hand.

I do take your point about being a regular customer, but without wishing to sound harsh, BA has hundreds of thousands of regular customers. We're all just numbers to them. IAG (BA's parent company) is currently making money hand over fist, and that's all the while annoying a great many regular customers with cancellations, delays and other trials and tribulations. So I wouldn't personally put too much store into them being helpful just because of repeat custom.

I think in your case I would be hopeful, rather than confident. You might get someone who agrees that, since it was BA's actions that stopped you getting the TPs, that you should be awarded them, as well as seeing the bigger picture that this will drive your future custom.

Equally, they might stick to their position and if they do, there's not really a lot you can do. You can decide whether it's worth working back up to Bronze/Silver (and as noted, the forum has lots of info to help with that), or you can take your business elsewhere if that makes sense.

Good luck, and please do report back with whatever outcome you get.