This is 600m2 in amn industrial unit , not a patch in a bathroom.
I once did a mould clean up in a hotel in Prague, the dry risers were full of mould, we used HEPA vacs first , before starting the clean, no bleach of any kind was used. Writing up the protocols(risk assesments and method statements took 3 of us days to complete along with several meetings.
THe clearance testing bill was 8k alone . the total job value was $1.2million . A bit of bleach on concrete/comcrete blocks would get you laughed off the job in seconds.
The original poster said this was an industrial unit , what if it is to be used for food production? or electronics , " oh right mate ,we are gonna use gloves and goggles and some bleach it will be a tp job"
I am afraid the cleaning industry is littered with people who have limited knowledge and training ,who rely on basic knowledge gleaned from forums who think the job is easy/simple/quick.