I've had something similar on my 2007 MCS
Unfortunately, it was my fault. My spare key was in a drawer that was close enough to the car to keep randomly unlocking it and locking it. Must have been items in the drawer pressing the buttons on the fob as things were put in/taken out etc.
I came out one morning to find it completely unlocked and both front windows all the way down. It had rained overnight so I had a nice wet seat as well.
Since i moved my spare key out of the drawer, I havent had any troubles at all.
Not sure it's the same issue but thought it was worth a punt.