Your background is good. cambridge and ivey's application is not difficult, but berkeley is quite difficult for chinese, especially for you from mainland!
For Cambrige, two special requirement, GPA: >3.3; TWE:>5.0;
For Hass, I am not sure.
Last but not least, it is definitely not bad to have a pro for writing essays, but you yourself should dig into yourself deeply first. The deeper, the better.