Hi there - the interior light isn't on, but about a week ago I broke a key off in the passenger door and haven't been able to extract it yet. I can lock the door from the inside, it also locks from the central locking (by using the key once the doors are all closed) or pushing the lock across on the drivers door and then closing it.
Once all doors are locked the interior light goes out and the doors can't be opened unless you use the key in the drivers door...I'm not sure of the timing, but approximately 15 seconds to several minutes an alarm of sorts starts to sound and the door ajar light comes on in the dashboard.
The vehicle doesn't have a security alarm installed so the 'alarm' sound as per my previous message is this low tone repeating beep from within the dashboard somewhere.
I have not sent the vehicle to anyone for repairs either, you would be the first person I have checked the problem with!