In my opinion, Hybrid or even CPA is never a good idea.
While I find it strange that they don't exactly name the reason for the termination ("fraudulent activity"), and while I have not worked with them, I give them the benefit of the doubt, because: if you would have brought them good quality traffic, why should they stop working with you after you've brought them 11 customers? If the quality was good, they'd approach you to bring more traffic and increase the current deal!?
"Semper paratus!"
My BTC Address: 1F11EJvSAab5vMQgGWGQMASr9T7LCkZjvb