I’m really sorry this happened you, not only did they they have you grabbing your ankles they were wearing an extender. I have a couple questions, was the particle board OSB? OSB is an acceptable sheeting underlayment as long as it needs the manufacturers specifications. The permit they pulled, did you see it and did the city come out and do a final Inspection? They would have come out and pull a green sticker on a window. You can look up your address online to see the status of the permit. Section 105.2 in the COB building code does not require a permit for replacing a roof. Also if they pulled a permit and added structural repair modifications then a modified permit would have been needed, section 114.14 states thats its a violation. Unfortunately the work they did you agreed too, they only thing you could look into is the permit if they applied for one and didn’t you have a case to pursue if you wanted to. Also in the future advise for you and anyone else, if a contractor has concerns about structural elements of your home, call a structural engineer, I am a structural engineer and do this types of inspections for a few hundred dollars and it could have saved you Atleast $7k I know several contractors that would have done that work for way less than what they charged you. They more than doubled the price of that work.