7th complaint in one year and this was the worst experience you've had to date? Either you have been exceptionally unlucky or your threshold for tolerance of what "just happens" is different from mine.

Others have commented on the most effective routes to resolve the two issues you had (tier points and seats).

I'd imagine that maybe 25% of my flights have niggles (poor cleaning, changed seat, bus / very remote gates, late departure, poor boarding, average service, MAN airport) but I've only complained twice in the last year - once for no wifi when I really really needed it and once about boarding process (and that was only after I had specifically been asked by BA to lodge a complaint).

Yes if a service advertised isn't delivered then it's sometimes disappointing but I'm not sure I could cope with complaining every time, especially when BA's initial response tends to be to dismiss / minimise / misunderstand the complaint, making you feel even less valued!