Once the notice of the AGM is sent, the date is set. The owners reasons for postponement hold no weight in terms of the Act.
The Act does make specific mention of what needs to be provided in the notice of the AGM, and the compulsory motions required. If your notice does not comply in these respects, then the meeting is considered not yo be correctly called, and any business conducted at such a meeting is invalid.
Unless you have been provided with a proxy form by the owner, the usual proxies have a maximum duration of two AGMs.
My experience of small complexes is that they tend to run because if the efforts of a few, but often the OC fails to comply with the Act. It’s when a new owner comes along that the status quo is challenged. The new owner may seem to be a troublemaker, but in fact us challenging the OC to start complying with the Act.
Unless your committee is well up on the Act, I Would recommend engaging a Strata Manager. They can be helpful to help thecOC comply with the act, as well as being an independent party in settling intaowner disputes.
You haven’t provided a lot of details of your OC situation, but the new owner may have grounds to have a strata manager appointed by the court. Better to get this sorted out by a Strata Manager you appoint (at a GM) than to have one appointed by the court.