Confused by Mind control

One siren took control over two my soldiers, my priest took control over that siren. Why my soldiers, controled by siren under my control, continue atacking my other soldiers? Who spend 2 WillPoints per soldier for continue control?

I’d have the same question about an unconscious siren. I had paralyzed it, but it had already controlled one or two of my soldiers. And when stunned, it didn’t release control, so I had to kill the siren, because I didn’t know if the soldiers would have ended M.I.A. like in the first XCom. Also, I really didn’t want them killing my team while I was hunting for the last Pandorians…

So, would it be possible to correct this ? Unless, of course, it is the intended result, because of the way the “mind control” works. But, if that’s the case, how come killing the siren gives us our units back ?