Probably not what you want to hear, but your experiences are nothing compared to what others have gone through. On your 3 specific complaints:
1) I'd say a 2.5% refund is ok, although BA's service recovery is derisory and £100 would have been nice. Those days are long gone though - passengers are now treated as a necessary evil by BA.
2) You really have to take responsibility here - yes, BA's systems are not the best, but I can't see how you can blame anyone but yourself here.
3) This could be on the DYKWIA thread, but if BA has changed their approach (and BA staff are renowned for telling hearsay as facts), then I can understand why. Continually upgrading their most frequent flyers leaves little incentive for those passengers to book the higher class of service.
I'm no BA apologist, but I'm not sure the above is a valid reason to find another airline to fly, unless you can identify one that offers you the same routes for the same levels of price and service. You are correct on one thing though - BA no longer value their customers.