The tank was childish for behaving the way he did marking you, but he was right to be annoyed if you were texting and missed a boss. If it is an emergancy sure just quick in /p say sorry important rl thing brb or whatever, do your thing. Everyone is happy.

By marking him every boss fight you antagonised him into doing nothing. You were just as childish as he was. Two wrongs do not make a right, next time, be the bigger man or woman. Ignore the fool and carry on. Or try a vote kick if they are being majorly unpleasant.