Totally fed up, I think I've been ripped off.
Been out again today wearing my gear s3 and it says I have done 0 floors, my wife's fitbit shows 11 floors. This is now normal, it seems I only ever walk on the flat (I don't)
It is clear from the number of threads on the internet that this is a longstanding problem that Samsung have no interest in fixing - they've sold the dodgy product and walked away
This will be the last thing I purchase with their brand