W221 2006 S600 rear entertainment system remote control

[Darshan]

Recently purchased a low mileage S600 which I may regret. I will let you know. It has a factory fitted rear entertainment system and after much frustration I realised you can only change the TV channels etc in the rear with a remote control. I purchase a genuine Mercedes rear remote part number A221 870 3889 which is working but it will not operate the entertainment system.
I am guessing it needs pairing with the system.
Does anyone know how this is done?
Thanks

 

[DesignJunkie]

Found this on US forum MB World here. And elsewhere say you have to go to dealer (or can registered indies also do this?) to programme the remote and headphones. My new to me 2012 350 L doesn’t have any remotes or headphones so expensive to buy on eBay then pay for coding vs my daughters using their iPads and iPhones - might live without it but they’re 14 & 18 so easier than young kids!!