Sounds like you need to contact an experienced construction attorney who can review the contracts you've signed and inquire about other facts related to the dealings between you and the contractor. Only after reviewing the Ks can the attorney give you proper advice. You should contact local counsel.
California law requires a signed change order for all extras done on a home improvement (remodel) contract. It's hard to tell if these bills are all legitimate or not. You should ask the contractor for a breakdown of the total bill and talk to him about any item you dispute. You may need to consult with an experienced construction attorney if you can't resolve this yourself. Roofing disputes are very common.
I would need to see the contract and other documents you signed. Generally, you should only have to pay for items you agreed to, however, yours is not an uncommon experience as a homeowner dealing with a contractor.
The issue is whether the contractor overcharged you for his work. Therefore, we need to examine the contract along iwth all change orders that you and this contractor agreed upon. And we also need to assess the fair value of the work performed at your home. If the fair value established through another contractor (or construction expert) is within narrow range of the moeny asked, I just will pay this roofing contractor and call this dispute off. If $100 worth of work done, then, pay him a narrow range within $100. Edward C. Ip www.lawyer4property.com
No attorney / client relationship established. The answr is for discussion and general information only. The lawyer had not reviewed any documents or contract prior to the above comments.