This agency really mess you around, and they hold grudges! I once cancelled a shift at 6 hours…read morenotice once because I was so ill I couldn't get out of bed. Instead of just accepting that I couldn't work they shouted at me for only giving them 6 hours notice (I called at 7am!) and then tried to convince me that I wasn't too ill to work, and accused me of lying about being ill. I didn't get any work for 2 weeks (after I was better) despite there being lots of work and them practically begging other people to work.
A few weeks ago I had to cancel a shift for the next day because I was severally injured on my way home from work (I won't go into details, it wasn't nice, I had to take over a week off work, but that's what happens when you have to walk by yourself in the dark). I called the emergency mobile, as it was around 11pm, and left a voice message, as no-one answered, and then sent a text to it, which I never received a reply to (despite the fact someone is suppose to answer 24 hours a day, 7 days a week). I did not get a response until 7am the next morning, via email, giving them 1 hour to find a replacement, yet I'd been shouted at for only providing 6 hours notice.
On another occasion my shift was changed to a different one with a later finish, which I could not do. I had informed them that I could not work past a certain time. When I rang to query this I was informed the shift will finish by the time of my original shift. Having been told this before, I said that I wanted 100% guarantee (it was very important!!!!). They then cancelled the shift, saying that my other shift had been cancelled (I know it hadn't as when I rang they informed me that it hadn't been, but they really needed people for the other shift), and that they didn't want me to lose out on a shift (the shift was actually shorter than the original one, so any pretense of them being nice was totally false) so they had given me that shift, but if that was my attitude (I wasn't rude, and I did apologies for coming across as rude) then I could do without a shift.
I have also had shifts cancelled at 30 minutes notice, been told to arrive for a shift 2 hours earlier than I was actually needed to, been given the wrong location/access/uniform details, and not been paid on time (several times) and then had them ignore my phone calls/emails asking when I will be paid.
I am not the only person to have had issues with this agency, my collegues moan about them all the time. They continuously have to recruit people due to the amount of staff that leave, or refuse to work the stupid hours they ask (I know people that are practically forced into working over 100 hours a week, every week. The money maybe good but they are constantly exhausted and ill. And as I said before hold grudges, and they don't like it when you don't just go along with what they want. These people can't afford to get hardly any shifts, they have families).
I am currently applying to in-house casual jobs as I know from talking to members of staff that they are much less likely to mess you around.