HI
I have just gone through something slightly similar. Be careful not to allow this to escalate emotionally with your SC. Get as much information as you can from your council. There may be records of the changes made to the original design in council records. Going to NCAT is not an easy quick or cheap exercise. Neither are lawyers. Your OC will probably have legal defence insurance while you will be paying our of your pocket. So I agree with getting legal advice but be proactive find out as much as you can yourself. Make sure the lawyer is Strata Specific. Keep the lines of communication open with your committee, a compromise might be easier than months or years of legal action. Keep a diary of events.
Lady Penelope is right about taking this to court it is very very stressful.
Good luck