2013 Superb 1.6 electrical issues

For a while while driving the engine would stall for a split second and the dashboard would show as if just had the ignition switched on, this was random and could be days or weeks before it happened again. This week while pulling up in a car park as soon as I stopped the engine cut out and the dashboard went blank, turning the ignition key did nothing, after about 30 - 40 seconds which seems an eternoty when you can't start the car the dash starts to flicker for a few seconds and then all is well and can start the car again and get on my way. Any ideas on the cause from you more knowledgeable guys on the cause? Car is a 2013 1.6 diesel Greenline hatchback.

Edited 1 hour ago1 hr by Fekker