Pull the bugger off of you
You can buy our cheap LOTR Gold for getting the useful equipment and helping you level faster. One thing to keep in mind is that in tough situations it is all about stacking the right tools to get the best benefits.
Theoretically you could just sit back and throw heal and a hot here and there. Not bother with changing from offensive to defensive target and no one would probably say anything but in order to contribute the most to your group you have to work your butt of as a chanter. You might pull aggro if you are solo healing or heavy backup healing, especially in combination with Word of Protection Spam and stun attempts. Do not sweat it; you should be able to stand your own until the tank can pull the bugger off of you again.