If the sliding doors are double glazed then you can have them considered as a minor renovation. But seriously, I think this has been going on for so long you either need to get lawyers involved – and hope you can recoup the costs – or ignore the committee and just get the work done and let them pursue you, or let it go.
You could even hire a lawyer to come to the meeting and (as our scheme did recently) scare the owners with stories of having to be cross-examined by a barrister as to why they voted against the motion. That said, that tactic annoyed everyone so much that they turned against the committee and rejected the proposal anyway.
FYI: It is absolutely legitimate for a committee to explain what the motions are and how they think owners should vote – provided the information they are presenting is truthful and in the interests of the strata scheme.
The new strata laws require strata committees to be honest and fair and if you can prove they haven’t been than you might have grounds for having the committee or individual members of it sacked.