RE: Overheating E320
Are the wires in the harness sufficiently damaged to show exposed copper?
As Battlecat has stated this is a common problem but sometimes it is only the outer fabric or similar bundle packaging material that has deteriorated, in which case there isn't a problem...at least in the short term.
Dependent upon the extent of the damage why not repair the damaged section. If the damage is extensive you have no choice but to replace unless you are really into DIY.
Strange that you sould have a bad harness and (I assume) two fans all at the same time. Did the dealer say about the fan controller was OK? What about the fuses?
I suggest that you, or somebody on your behalf, should confirm that the fans are dead by applying an independent power source.
I suspect that you may be lined up for a "revenue" opportunity.
Hope this helps.