This sort of appeal is very different to an ordinary s82 objectors’ VCAT appeal against a council decision to approve a planning application. Once a planning permit has been issued, an objector who wasn’t notified of the granting of the permit for some reason can only appeal against the permit under s89 of the Planning and Environment Act.
However, you must be able to satisfy the Tribunal that you’d suffer substantial disadvantage AND that it would be fair to all parties to cancel the permit, otherwise the developer may ask for costs to be awarded against you because your appeal could be considered as an unnecessary cause of extra costs and delays in construction.
So objectors should always get legal advice before lodging a s89 appeal.