Well I will push this way. But although as a professional I should know about that he was not passed the information about the cement type from the main contractor.
Not to bad then...if that's possible..lol
At least it's not 100's of meters.
If its any consultation your not the first to experience these problems and you won't be the last !!
Lift tiles, park backside in the garden with a grinder, and concrete grinding disk. It will be a horrible job, but you should be able to save them for re-use.
@CJ thanks for the advice, a hell of a week end ahead... I'll prog start with a chissel on a well levelled floor to get the most off first. @Andy... well I'd rather not me not everyone have these issues
I find the best way to remove adhesive from tiles is to cut through the adhesive with a grinder 20mm apart in both directions then the small squares pop off easily with a chisel. It should be the tiler doing it though!