Yep quit as soon as if it is making you unhappy. With that much saved there's no worry about finances as far as I can see. Take some time off and pick up another role when a decent one presents itself - maybe with less hours and better conditions
Thanks everyone. I've thrown my CV out to a few recruiters and managed to line up an interview for tomorrow morning with a big bank.
[..]
Funny enough, I really enjoy IT, I wish I could switch to systems admin or programming or something but not sure how I could do that without going back to school.