There may be some lenders in Australia that will let you postpone your repayment date, which may be when you are expected to return the full loan amount in lump sum. On the other hand, if in case you have opted for a doorstep loan, then it may be possible to get an extension.
However, if you are having any kind of repayment difficulties, then without wasting your time further you should speak to your lender. They might look into the matter and see how much you can afford to repay and will also suggest different ways to repay your loan or may offer extended repayment term.
Alternatively, some companies might prefer to change your repayment schedule, so that means you are still paying money when you will have and that includes your due date but your repayments are lower than you have agreed before. However, again that would mean you will be charged extra charges and fees. This will ultimately increase the total amount that you are supposed to pay off.