Ok, well, first off you need to work on grammar. You have only five capitalized letters in that entire post and your sentences seem to go on for a few extra miles with no gas. You could also space things out more too.
Spec can make a huge difference in performance. I can't talk about priests, but the lock should be able to keep any and all dispells/cures out of the question in arena via Unstable Affliction. This effectively cripples your opponents healers and runs them out of mana quickly, trying to keep health up along with PW: Shield.
Topple this on top of your priest mana burning their healer and you don't have to CC their healer at all. Use that CC towards backup healer or DPS and the game is effectively 3v1 for at least a few moments.
As far as tactics are concerned I would suggest dispatching of one of the opposition's DPS first to take pressure off your healer and then slowly pick away at the other two focusing on whichever one is more of a threat.