it's good that your guild want to help you gear up but they still have to remember that you are undergeared and "learning" tanking these places. It's the usual problem will face constantly from your dps......mainly because they are so set in getting to the top of recount that they forget about the small issue of overaggro. If your Mage died from this tough shit it's his fault. Now if you where a fully geared icc tank and this happened I would say it's proberly your fault but your not so chill.
It's a learning curve both for u and them and as soon as they click it will be fine. Toc normal dosent require 10k dps to beat a boss so unless it's a badge run or a boost run for a dps or healer they should calm down and concentrate on aggro and helping you progress so you can go onto bigger and better things.
So long and thanks for all this fish