I had the same symptoms when the water pump failed (this year) on my 93 300E.
I've since learned to do a lot of work myself, and I understand that it is a frustrating and time-consuming task, but is a DIY job.
I wasn't very sure of my skills then, so I gave the dealer $860 to do the work. You can save over $500 if you do it yourself...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car