Unless there is other information, the way that strata went about it is incorrect.
Reading Section 236 of the act, seems to be that only the tribunal can vary the UEs. So a bylaw will not affect the UEs.
With the order of the tribunal , the OC goes to Land and Property information and registers the new UEs.
Until the new UEs are on the title certificate, they have no effect.
The act also says that the OC must register the new UEs within 6 months.
I think the poster is compelled to pay the levy according to the old UEs.