Spent a happy afternoon disassembling the front passenger door on our 05-plate Fabia, after repeatedly observing the following behaviour. If the car is unlocked with the fob, and just the front passenger door opened, it re-locks itself after a short while as if it doesn't know that door has been opened.  Not 100% of the time, but more and more often. Also;  and noticed as long ago as a year back, is that sometimes when driving, the car either attempts to or actually does lock itself, p