Stripped Webasto wiring...

[windy]

I've been having issues with my 3.0D not starting quite a lot now. I've checked that it goes to sleep, that the alternator works, and that the drain when sleeping is as it should be, but it still drains a battery within days.

Anyway, while having a nosey about, I discovered these wires have been stripped at some point in the cars life — they go to the Webasto heater.

Any ideas why?

Also, I think there's a cover missing from here too?