Well, there are many different groups. You can go with a larger and more known group, and run less risk while paying more, OR you can go out on a limb and guess on a random company. I suggest using a blank account rather than your main, if you can afford one. Several of them say "No bot" But if you log on and trail em, or try to talk to em (They pull the afk crap) But, say you'll report em for botting. Most wont even reply to this. Thus theres a 70% Chance that they are botting your toon.
Pay with a CC and cancel the payment via your CC Company if they don't deliver what was agreed upon. That and change your PW as soon as they're done.