Customer service is right, it is up to the dealer. Customer service can only make non binding arbitrary suggestions. Speak directly to the service manager and not the service writer, if that doesn't work speak to the dealer principle (owner). Another option is to take it to a different dealer.
Replacing the radio likely won't fix the trouble anyway as it is more likely that the problem is with the antenna components (the mast, the base, or coax). Replacing all three has always fixed that trouble for me.
