robinFFM

Hi all, newbie here. Please can someone help? We have just bought a A6 Avant c6 2006 model with MMI and Bose which isnt working. We knew this and hoped it would be an easy fix. I have a replacement MMI unit for the rear but it has not made any difference. I have read i need to get it reprogrammed by Audi. Is this correct? Should i see anything working before its reprogrammed? Thanks all.