Wfh allowed for FT workers but not PT

I made a post about this issue before. But still I’m having ongoing issues.

My employer allows full time workers to exceed their one day wfh, in circumstances at the individual employee’s discretion. Examples: they are sick and have long term symptoms, need to attend an appointment, train lines down, need to be home to receive a delivery.

Their policy on wfh is only full timers are allowed to wfh (one day a week) and during the hours of 8am - 5pm. This is not always followed by employees as shown by example above.

I work part time because I have caring duties for my son. I have the same duties as any other employee.

It appears I’m being denied the same flexibility as other employees. And as a result I have no annual or sick leave left. I have had to come into the office while recovering from respiratory virus symptoms when it would have been favourable to me work from home. If I have a doctor appointment for my son who has health issues, I have to take the whole day off.

Can someone please give me advice about how to proceed to better my situation. Or maybe suggest how to request their wfh policy be changed/is unfair to other staff. If anyone knows something about the fair work act that stipulates how this is potentially discrimination.

Thank you