Although I can sympathize with the story, this particular aircraft had been in their hands just a couple months. Its first commercial flight was just a couple weeks back. Maintenance isn't the issue here, clearly.
It is. Maintenance was aware of the pressurization warnings on this plane. They did nothing.
Planes are incredibly complex and have little problems like that all the time. It's not a safety issue.
This was a brand new aircraft, this is almost certainly a manufacturing defect of some kind.