Did eventually get through to Currys and they offered to return it but after scheduling I did some further tests showing oven was basically OK so decided to keep it. The error 20 only shows when been powered off for long periods. Still have the 12 month cover if plays up further.
Yes made in Turkey on side, but the hob also by Logik is made in China.
Agreed probably best to keep on all time, I measured it at 3W power draw or about 7.5 quid a year.