Hi,
Recently I had one of my decker PC track down a source inside a Virtual Reality host. When he arrived there, he found two Reality Hacker torturing his source through the matrix. Here is how I have implemented that, and I would like to share it - in case some other GMs wants to the use the trick:
1) First decker uses Lockdown to prevent the target to simply jack out - that much is obvious, but the victim can still either use the Reboot Action (with dumpschock) or try to Jack Out. He obviously uses Biofeed back to inflict real, bloody damage to his victim...
2) Second decker has MARKs on the commlink of the victim and wait for the victim to try to either Jackout or Reboot and execute a Spoof Comand, at the same moment to cancel the user command, trapping him or her, inside the Matrix.
Of course, Jack Out being a simple action, one could argue that the victims could at least get one JackOut action by turn - so maybe you'll need one more decker or Agent to fully cover everything.
I'm pretty sure there is arguement other to make this all manoeuver "illegal", and please share them, for the sake of discussion, but I found it a nice way to allow some "ganger" to bully people through the Matrix. It's not easy, and it requires at least two persona acting together, but it is possible.