if it just started happening today- it could be that there are power surges in your area due to the heat!
noticed you are both in melb!!!
So the problem could be coming from the main exchange rather than your house
HTH
A way to check your fridge Cai is to get a powerboard with safety cut off and put it on the fridge to see if that cuts in or out!

HTH- just an idea . .. .

odette