Poor workmanship and service

We bought a house in South Hills, Paperbark. it's only 2 years and 3 months living there but there are cracks on the wall, a few months after moving in there was leakage on the basin and developer wasn't willing to assist after i reported the issue. The walls are moulded because the houses don't have air bricks. The ceiling collapsed a few months ago, lucky the kids weren't nearby when it happened.The sink also came off, didn't bother to report the sink because i know they won't help instead they advise you on how to do it yourself. Calgro is not willing assist in anything and they told me to contact my insurance, it's hardly 3 years but already the house is falling apart. Im disappointed in the poor workmanship of Calgro, crime is out of hand in that area, the area was advertised as a gated community but there's no access control. 4 cars have been ****** in the past 2 weeks. I wouldn't advise anyone to buy a house from Calgro even my worst enemy. Buying a house from Calgro was the biggest mistake.