I worked for 3 shifts all in all, before giving in. I got no signups in my first 2 shifts so received a disciplinary. You are left to your own devices by team leaders who seem to struggle to know what to do themselves (some are promoted after just 2 weeks), I was threatened to have the police called on me at half 8 for knocking on someone's door.
The 7 pound an hour was great, except it cost around a fiver to go to wherever we had to go to, plus on my last shift, I was getting angry phonecalls at 1pm because I'd not come into the office yet because I was in a lecture, and my shift didn't start til 3. The 18 hours a week pretty much was 25 hours and a lot of time had to be invested in learning about the charities you were working for too.
I have a friend who has stuck with the job for over a year now, but he works 'full time' there - and he's also a reason I wouldn't go back. The 'successful' people there tended to be the drug dealers/stoners/piss-heads who just so happened to talk the talk, and the lax approach to the personal hygeine, appearance and etiquette of the staff who are representing respected charities did concern me.