My retrofit RNS-E Navigation Plus has been working perfectly on my 2005 Audi A4 Avant since I bought the car 5 years ago. Last year it started to develop an intermittent radio reception problem on all wavebands and now it appears to have stopped working altogether. Occasionally I will hear a faint signal which appears to be the same no matter what station is selected. Occasionally it will change stations and the reception will improve for a split second. I've removed the unit and cleaned and checked all connections. I've removed the rear boot trims and checked all connections. It has a shark fin aerial which I'm told contains a component although removal of the rear roof courtesy light shows nothing obvious unless it's integrated into the fin itself. Everything appears to be ok on all components with no obvious corrosion or broken contacts. Everything else on the unit works perfectly including phone, sat-nav and sd card readers. The radio scans and shows stations in orange and with the unit removed the feint signal gets slightly stronger but drifts in and out as if the aerial is not connected or the code is not enabled. When power is disconnected to the unit and then reconnected, the radio does not request a code input. A VCDS scan does not show any radio faults nor does it identify a radio control module. Any ideas anybody?