Ran into the issue myself a few weeks ago, highly annoying. Bioware, for reasons untold, will never openly discuss/clarify the matter.

If you're going to run around alone and focus on quests, remember to enable Vette's abilities through her hotbar. Group up as many mobs as you can + Warrior Smash + Vette C4 = quest completed.

No reliable way to "kick" / lock out a healers spells without blowing general 30-60 sec CC cooldowns. No way to reduce healing done. Unlimited mana. Permanent guard buff on healer. I'm surprised it took this long for people to catch up on how all of these things combined is a problem.

Why do you (almost always) forget buffing yourself with class-specific buff after you've died the first time?