A colleague of mine has had this issue and the building company replaced all the nails, took a week or so ( he is in a lifestyle village ) and they had to do more than just his place.
Before going too far, dig out all you paperwork and consult your lawyer.
You lawyer will know ( hopefully ) the best path to take.
It might cost you a couple of grand but they should be able to get action faster than you going in saying the building act or whatever. The lawyer wil be able to say yes you have a case, not you dont have a case or under this act section, paragraph etc.
John