If you want genuine I think you will be very very lucky to get one.
This link shows how the socket is wired
https://caravanchronicles.com/guides...fault-finding/
My comment would be not to make pin 9 a permanent live from the car as leaving a caravan connected could flatten the cars battery.
Cable, split charger (TEC3M) and by pass relay (TEB7AS) can be easily sourced
macafee2