The only way you will resolve this may be by just going ahead with the renovation on the grounds that it has been approved or taking your SC to Fair Trading and NCAT on the grounds that they are failing in their obligations under Section 232.
What was the process by which they overturned the previous approval? Was there an amendment to the original application? Did they raise the issue again? What is their objection and waht were the grounds on which they refused? Was it not approved as a special resolution in the first place. If so, the only way that can be rescinded is through another special resolution at a general meeting.