Definitely UNRELIABLE...
They projected a two-day repair, but ended up keeping my car much longer--four days--for a simple rear bumper replacement. Also, they told me that they would call me when they receive the parts, but never kept that promise, either. They do not call you with updates, either, although they promise that as well. Communication is horrible and reaching your estimator is difficult, as they are always away from their desks and they don't call you back if and when you leave voice messages.
They work with Hertz and Enterprise for rental. I chose Hertz and regret that big time, too!
Long story short, having to work with these guys was a painful experience for me on top of getting my car hit in a parking lot! I do NOT recommend Collision Authority under any circumstance!