I Rent A Commercial Building Consisting Of 2 Floors.

i would actually seek legal opinion  on this, because under Australian law, if this sort of things happens in a residential situation, the landlord is obligated to fix it forth with. Do not whatever you do, refuse to pay your rent.  Keep it up to date, otherwise you'll end up in legal trouble.

I would seek legal opinion with your situation.  I would have thought that repairs and maintenance would be a part of the terms and conditions of your lease contract.  I'd keep a diary or some record of the conversations you have with the landlord, or better still put all of your communications to him in writing, so that you have a record of what you have discussed.  You may need it, if it comes down to legal argument at a later date

depends ....on what your contact says....also because you have products, ceiling, and other damaged property....you should have had insurance for this....building, products, and other things.

depending on how your contract reads really this will determine the out come of your case.  now because of the mold this also creates enviromental issues...

you said that you told the owner several times of this problem....was this verbal, written, or ?  this will also determine the outcome.

getting out of leases these days has became very difficult without paying fees or some time of fine.

but like i always say...you never know until u try...but talk to an attorney..let them see your contract and they can best determine what the best route for you to take is, and most of the consultation is free!

good luck and hope this helps