It sounds like a nasty response from the property manager.
Please look up Residential Tenancies Act 2010 to familiarise yourself with your rights.
Also read your lease agreement. The standard residential tenancy agreement can be found here. Both the Residential Tenancies Act 2010 and the lease agreement should indicate that you are entitled to have something like the oven in working order. Page 8 of the standard residential tenancy agreement document has a heading “LANDLORD’S GENERAL OBLIGATIONS FOR RESIDENTIAL PREMISES”.
You should also have received a condition report. Both landlord and tenant complete the same condition report at the start of your tenancy. It records the state of the property at the start of your tenancy.
In the standard residential tenancy agreement, 60 days’ notice is required for a rent increase. On page 5 of the standard residential tenancy agreement, it says:
“Section 42 of the Residential Tenancies Act 2010 sets out the circumstances in which rent may be increased during the fixed term of a residential tenancy agreement. An additional term for this purpose may be included in the agreement.”
There is a rent check tool on the NSW Govt’s web site: https://www.nsw.gov.au/housing-and-construction/renting-a-place-to-live/rent-check
It uses rent data collected from rental bond lodgements to give you an idea of how much rent is being paid for similar properties in your area. Use it to see if the rent increase is reasonable.
Addit: added a link to the standard residential tenancy agreement. Mentioned the condition report. Correction to notice period of rent increases. It should be 60 days.