I bought pro-activ, have used it a couple of times actually. Don't worry, there is no dramas cancelling it. You just ring them up and they stop. You can also go on the website and make the orders less frequent, I did that coz I found I didn't need it that often. Last time I cancelled it after they'd just sent another one too and I rang them and they said send it back and they'll refund it!

I also have Sheer cover but I didn't buy it. I think you get 2 colours to blend or something so someone bought it and didn't want the other one so gave it to me. It's ok. I think it's good coz it's mineral foundation and doesn't make my skin breakout. But it's pretty messy, lol, and can look a bit powdery sometimes, you have to put it on maybe 1/2 hr before you go out then rub it in a bit more after a bit I find. Just have to make sure you get the right colour. Overall I'm happy with it and when I run out might buy it again myself.
Good luck!!