AF1:
You can definitely buy the pins and plugs from MAN I’ve done a couple of sets.
I take it all back! I went up there to ask and we started trying to identify the plug from the drawins on the computer. After half an hour looking at the drawings and getting not very far the guy said “Let’s go and look in the stores” where they had what I can only describe as a drawer full of electrical junk on a rack. In the drawer was a box of miscellaneous pins, and I spotted just the pin I needed in there immediately. It was close to the end of his working day and he couldn’t be bothered to write out a bill for one pin so he just gave it to me. 
Another thing to check while your on is your centre wiper spindle loose or worn as they can let water into the cab accelerating the corrosion on those plugs.
Ah, that’s where it must be coming from. I’ve been wondering how the water was getting into the cab. Thanks for another good tip, I’ll take a look.
But first I’m going to attack that connector…