I would also advise the secretary that an EC decision CANNOT override a AGM decision and that if the AGM decided not to increase security the EC cannot them decide to do the opposite unless they are prepared to accept that they (the EC members) could be liable for the cost.
This also applies to the Strata Manager and they (SM) could be liable for costs incurred that the AGM voted against if the Strata manager ignored the vote and did the upgrade anyway.
Remember The SM and the EC are responsible and accountable to the Owners and they have to obey instruction from them if the owners passed a legal vote.