Just to make sure: you did tell the others that you're tanking right?
Because if a tank sucks that's one problem, when a Dps decides he's the new tank because the player that qued as tank sucks that's another.
From me on my healers you would have gotten a quick "stop tanking", for 2 reasones :
1) There's a tank already, and you're just making me work twice as much keeping you both alive.
2) At HS no one has a lot of abilities, not the tank, not the dps, and definitely not the healer. So expect diminished resultes even from good players.
YEAH the player wasn't responding so i told the healer and other dps that i was going to start tanking. The healer started to heal me during the fights and so it was all good. Thats also a true point but i was only 18 and the vanguard was 20. I even had one taunt so i would hope that he would have one too.