Since it is my son's car, I hadn't even bothered to look for such a switch, On my Superb, all the mirror controls, electric window controls, and door locking controls are on the driver's armrest, and I had just assumed that his car wasn't so equipped, but I've just nipped out and the car does have central lock and unlock switches down by the bottom of the gear lever. In summary, the lock and unlock switches work for the rear doors and tailgate, and have no effect on either of the 'keyed' doors. To be honest, this is in line with the diagnostic help that I have been getting from @Breezy_Pete and @billwin. The method of agitating the doors at the same time operating the key on the opposite side of the car did suggest that the motor control in at least the driver's door could be made to work by the agitation, and thus needed repairing/replacing. You may be right about the passenger door motor PCB or other internal being damaged as the wires were actually broken on that door hinge, and we couldn't get that wake up during 'agitation'. I aim (Coronation fun and oaths permitting) to get at least the passenger one off and open this weekend and see what goodies lie therein. Will post the results.

Febi do some excellent door harness repair kits

 

https://youtu.be/u8kD4kXSDbc