Dashboard information - continuing problems

Recently my Fabia 1.6 TDI CR90 had to go to the dealers. This was because the glow-plug warning indicator would occasionally flash, and the car would go into limp mode. Switching off ignition and restarting would clear the problem temporally.

In the end the wiring to the ECU was replaced (at Skoda's direction). Since then all has seemed to be well - with one little quirk, the glow-plug warning light started flashing on just one occasion when the ignition was turned on.

An additional 'strange one' occurred yesterday. On returning home, I stopped, and before I turned off the ignition the idle speed had increased by about 200 rpm - when I turned off the ignition I noticed the word BATTERY showing on the LCD display.

1 - I did in fact have something plugged into the 12v supply at the time. (is that the answer?)

2 - Car has 4500 on the clock

3 - It was not entering regen mode (just come back from a 30+ mile journey at speed etc.)

It seems to me that Skoda have certain electrical issues currently?? - this is very disappointing in that my previous Fabia 3 pot (09 registration) never gave a moments trouble in the 2+ years of my ownership.

Is anyone else experiencing problems of this nature???

regards