having a problem with the radio it decides to work when it wants to and when i lose power the nav doesnt work either merc dealer tells me they think its an amplifier but wont gaurantee that it is and once i buy the amp and it still doesnt work im stuck with it and others have told me that if it works at all and it does about half the time it cant be the amp others have told that it could be fibre optics i have no clue but any suggestions would be appreciated

That's absolutely ridiculous. If I ever gave a client a line of crap like that I'd be unemployed.

What they're really trying to say is that they don't have a clue (they should!), and that you'll have to pay for them to guess what's wrong. Stories like this are the reason that dealers' have a lousy reputation. Contact the Service Manager directly, and explain that you're willing to pay a fair price to fix the problem, but you won't pay for any "on-the-job training".

thanks thats what i decided to do today i booked in for an appointment at another benz dealership and told them to figure out a fix i ll keep you posted