Load weight for subfloor

I hired a licensed flooring contractor to level my 1800 sq feet plywood subfloor using self-leveling compound. The initial contract is for 40 x 50 lb bags then they said it will take 150 bags to level the floor. When I asked about total weight and load, they said it will be within tolerance. Now, they want to add another 20 bags on top of it. I have serious concerns about structural integrity and would like to know if an inspection can identify issues so that I could take appropriate actions.