I began working for McDonalds shortly before christmas, because they were one of the few places in my area hiring and I desperately needed the money for christmas presents etc. Being 17 the pay was only £4.35 an hour, but I thought it would be worth it. Wrong.
Initially I did find the job reasonably enjoyable, they were giving me 8 hour shifts on saturdays which was what I had agreed to at interview, and the staff member training me on tills was really friendly. However, as soon as I'd done about two shifts they dropped the training and left me fending for myself, feeling useless if I wasn't quite up to their ridiculous standards of speed. One shift they left me on the dining area, on my own, on the late shift (meaning I had to get everything perfect ready for the next day.) Nobody showed me how to do anything, they just left me desperately trying to get everything sorted in time - I have never worked so hard in my life, but on my own with no training it was virtually an impossible task.
I still thought it was okay, worth the money, etc. and as i'm not adverse to hard work I didn't complain, just counted myself lucky i'd found a job...
This week they decided it would be fine to put me on from 4-30 till close, on a college night. This means I have to work from half an hour after finishing college until whenever they decide to let me go (probably about half 12) and then get up and go to college the next morning. As i'm studying 4 a-levels at the moment I specified at interview that I wouldn't be able to do that kind of shift. They don't care, apparently thats just my 'preffered hours' and they can make me work whenever they like. I'm handing my weeks notice in tomorrow.

-- A side note on ethics --
When I took this job i was slightly wary because they completely contradict everything I believe in. For a start I'm a vegetarian , but I decided to put that to the side and focus on the fact that it would just be a short term job. However, some of their practices sicken me, and I don't feel comfortable working there anymore - for instance their policy on drinks is to basically half fill the cup with ice, and a manager will shout at you if you don't put enough ice in. no chance i'm gonna charge someone 99p for essentially a cup of ice! the food is meant to come out of the production bin according to time cards, but the managers seem to think its fine to swap the cards without moving the food, meaning burgers can be in the lukewarm production bin all day and still get served to customers! No thanks!