As they never made the RNS-E for your year/shape of car then it is not as simple as young Arthur makes out.
Basically buy and A4 and trim to size, remove the metal strip at the bottom of the A4 unit, add a 2mm strip of metal at the top to hide the gap.
Bypass the TMC unit to join the two different canbus types together.
Pickup the canbus from the 26 pin connector and patch into the RNS-E harness.
If you have TV tuner in the boot, then swap it for a revision "C" or "D" module.