I would probably say to get a new car, too. It must kind of feel bad, having only just got it, and you might want to persist with it, though. If it was me, I might be tempted to try and stick with it, not wanting to 'throw money' at the problem and get another one..

But I can't quite see how the problems would either be rectified so easily, or whether new problems wouldn't surface. I mean, water leaking through the seals isn't good enough. You can try getting the parking brake off (on level ground!) and getting in and out.. or turn the music off and drive over some speed humps or something. You could also figure out what mileage you get, and compare to official figures (noting that their 'combined' consumption is often skewed somewhat towards a large component of country driving, at least in Australia.

However, the dealer's service doesn't sound inspiring, and it's not going to improve, either.

Sorry to hear that it's not turning out for the best, James.

A Golf GTI or Civic seem like decent choices. Or even a normal Golf.