9N - No interior lights.

Hi Guys.

Hoping for some help to sort a problem on my daughter's 9N TDi Sport. Since we bought the car we've had no interior lights working with the exception of the puddle lights set into the door cards. Fuses/Bulbs all seemed ok so checked the feed to the main interior light and found it dead. I suspect perhaps a multi-plug off at the back of the fuse board but this is just an educated? guess. Anyone came across this fault before or suggest a solution as I'm getting stick now the darker nights are coming in!