08CL63AMG

I'm at 95k miles, the service intervals were off from previous warranty work so this is regarding the 90k service for a 2008 CL63 AMG. Dealer said A service + rear differential service ($227) + fuel injection service ($208) + engine air filter replacement for 90k mile service. I've also been told by another local shop who I haven't been to yet that fuel injection service isn't ever required or needed and that they usually just clean the engine air filters unless they are bad enough to need replacing.

Can anyone shed some light on what is actually recommended?