Is there a difference with going with mediation or NCAT, and will the process take long?
You must go to mediation before you go to NCAT (except for in a small number of very specific instances, such as asking for a penalty for a breach of a Notice to Comply, or an application for the statutory appointment of a strata manager).
There is a long delay in the process at the moment but if you can show that there is a chance of severe personal or financial hardship you can apply for an urgent hearing, according to this NCAT factsheet.
When you inform the committee that you will be taking them to NCAT, tell them you will be seeking a costs award to cover your financial losses. That might focus their minds.