hysbenz

The dealership/stealership has told me I must have a new Audio Gateway for anything audio to work...HELP....is this the only solution?? They tell me it's a whopping 750$ to replace. There has GOT to be another way. I checked and placed a new fuse in the rear SAM to no avail...When I turn radio on only the logo appears then goes off. (never had Nav to begin) I'm willing to do some more checking but need to be pointed in the right direction. Thanks in advance!!!
2006 e350 base sedan