If you are currently in Australia and have a visa expiring in the next 1-3 months, you should immediately consult a professional on what your options are.
A visa expiring imminently can increase stress on yourself and your representative. Your options may also be limited the closer you get to the visa expiry date.
Usually, once you are in Australia, the options available to renew your visa whether temporarily or permanently are immense. Some options you may not even know about.
Do not leave this till last minute. If you know your visa will be expiring soon, you should immediately consult a lawyer.