Interaction between central locking and electric windows - Skoda Octavia?

Here's a problem that the local VW/Skoda main dealer seems unable to solve!

First of all the driver's door central locking failed: I could lock all of the other doors centrally, but could lock the driver's door only manually, using the key.

Then the situation became more complicated, and it became possible to lock the other doors only by pressing down their respective buttons before exiting via the driver's door, and locking this manually. On re-entering the car, these buttons remained down, but popped up when the ignition was switched on.

Then things became even more complicated: locking the driver's door manually caused the front passenger door electric window to open! Once only, the driver's door window opened instead!

Subsequently, the front passenger window would open randomly without command, but could usually be closed using the front passenger door switch, but not the driver's door switch.

Currently, central locking seems to have failed altogether, requiring that each door and the boot lid be locked manually and separately. The front passenger door window continues to open at random, and occasionally when the driver's door is locked manually.

It seems to me that there must be an intermittent short-circuit somewhere, either associated with the driver's door cental locking and window control switch unit, or associated wiring. The main dealer's technician has replaced the front passenger door window motor, on account of it being wet, but has made little more progress in three days, I am not convinced that he has adopted a logical diagnostic process. Any suggestions??