Thanks, you have 2 things to try
a) Try buying from Mercedes this firmware CD
W211 589 13 22 00
It may or may not work.
You must hold down keys 1,3,8 and then insert the disk.
b) If not, you need to replace the head unit (COMAND) - but your car has television in it, so you need one with Video input, which are hard to find.
See here
Comand Online Ltd :: Mercedes SatNav/COMAND :: COMAND, Navigation & Audio Units :: W211/W219 E/CLS MOST Comand Head unit with Video
Richard