Shonne:

I can't speak specifically to a E320 >> but for my 97 C230 I found that a normal sparkplug socket and a pair of needlenose pliers / hemostats worked OK.

Use the sparkplug socket to remove the plug from the cylinder head , and then the hemostat to pull the plug out of the recess.

Not exactly "elegant" >> but it works

When re-installing the plug > use a piece of rubber tubing over the plug cap and seat the plug by hand.. You DON"T want to strip the plug threads!!!!!