Possibly a coincidence, but.....
Had an awful experience with BA some months ago. Tech fault that took an hour or so to fix, but 3 hours of testing before it could be signed off by the crew. Boarded the a/c 4 times, were told on the 3rd disembarkment that there were BA reps with 'meal vouchers' waiting for us back in the gate area. They never appeared. All in all, a very frustrating 5 hour delay. Reported all this on the BA website when invited to do a survey a couple of days later. Next flight with BA (2 weeks later) and the next after that, I was upgraded on both occasions, outbound and inbound.
As I said, possibly a coincidence, but maybe the worst scores from the surveys are investigated, checked and remedial action possibly applied?