Ruben. It is an offence to carry out regulated work in Australia.
The leak you are referring to is behind a plastered wall, call a Licensed plumber. He will explore to find the leak & repair as necessary, when he sends th bill ask him to separate the bill into exploration & repair.
You should then claim against your insurance & any reinstatement & exploration should be covered.
Doing t yourself leaves you open to penalties & no insurance cover.