It’s important that you’re aware that you have rights and responsibilities around urgent maintenance.
Firstly, in most States, you’ll need to attempt to make contact with your Property Manager prior to doing anything further.
If you’re unable to contact your Property Manager, refer first to your Tenancy Agreement. It should advise who you’re able to contact in case of an emergency. It will also likely talk about what is an emergency item.
Then you’ll need to refer to your States legislation to ascertain how much you may be able to spend and in what time frame.
It’s always best to err on the side of caution and if the urgent issue isn’t going to cause any further damage to either yourself or the property then it might be best to wait until business hours.