leaking roof

My 1st floor rented flat located in Victoria has water leaking in from the roof. paint is peeling and mould growing. I only painted 2 years ago due to the same problem I guess.

It is an old building 1950's i guess, renovated cheaply a few years ago.
the roof is flat with a tar/pitch type sealing on top.(I am on the top floor) drainage is an issue, as i guess they continually block as no-one is clearing them.
My question relates to the property managers, they say they are currently looking at different treatments to reseal the roof, I guess the cheapest contractor will win.
Where do I stand legally how can we get the manager to do a reasonable job.
Also I would like to try to have mangement use the maintenance to keep the drains clean.
Any ideas much appreciated.