I am a condo owner and my Condo Assoc. got a loan 2 years ago to repair the ceiling, paint the building, fix the pool, elevators, etc. The majority of the owners are still paying that assessment which will be for 5 years. The property management company that we had 2 yrs ago stole the money and the new property management company just gave us a budget of 500K from an Engineering company which said the complex is 40 yrs old and has chloride based corrosion.
This budget seems way too elevated, nobody is comfortable with it, except for the members of the board, who agrees to do the renovation.
How can we check that in fact this is true, how do we now they are not trying to steal again?
Is there any organization that can investigate?

You need to check the bylaws. The condo owners may be able to demand an independent audit.