Hi looking for wiring diagram for 13pin socket fitted by Towbar to Towcars it’s on a Mercedes sprinter I had a new socket fitted yesterday he has wired up as 7pin it was for electric brakes on tow car it also had trickle charge to car he cut the wires and don’t know we’re they go been in contact with towbar to towcars they won’t let me have any diagram they said to take it to them but long way to go so need help Andy