...It might be something like the Ungarmax bug, but some elements here don't add up. New pvp stun or old pve stun, you can't be stunned that many times.

Next time... try to grab a video (if you have an nvidia card there's a built in recorder) so we can take a look. If they really did find a way to use holy in pvp, they can be reported (not on the basis of the video, but it will be in the battle logs so GMs can review it...)