This seems like one of those “easy way or hard way?” discussions.
The owners corp has the responsibility, without limit, to maintain and repair common property. They can hum and haw all they like but they will have to do it sooner or later and that’s the argument that you could take to the EC.
They can do this the easy way – just get estimates and get it done – or they can wait for you to get so pissed off that you take them to NCAT for a section 62 order to maintain and repair, and then they have to do it anyway, only now they have legal bills too.
But bear in mind that you want them to be fair and reasonable when it comes to all the things you want. Anything that affects common property – like bathroom and kitchen floors and some walls – is the Owners Corps territory. They could hold up your renovations for months, if not years, if you come on too strong.
Also, you don’t want them to fix the bathroom at their expense and rip it up at yours. So offer a compromise – tell them you will renovate the bathroom provided they make a contribution towards the repair of the shower seal but you will take responsibility for its maintenance.
Then tell them what you want to do in the kitchen.
Offer them solutions rather than problems and you’ll probably get exactly what you want.