Truma Combi 4 electrical failure

On my 8 year ols Broadway the Truma Combi has stopped working on electricity.
I see that CC had this problem in 2016 but reading the thread I am not sure what the final resolution was.
On mine 240v supply is ok and both the 12v and 240v 'slow blow' fuses are ok
When I set the unit to electrical heat at either the 900 or 1600 watt setting and at either 40deg or 60deg setting the symptoms are the same.
The control lights come on as expected but the yellow light which indicates the 'water heating' phase remains on.
The unit does not work on 'air heating either.
All in fine on gas.
I have had the unit out, which is a bit awkward, but since I check the pump filter every 2 years I know the process to get at it.
My thoughts are that either the elements or the control board has failed.
Does anyone have any input or knowledge of where I can buy the elements?
I would also be interested to know about experiences with the Truma Service centre near Derby. Am wondering if they would do repairs if I took the unit in?

Hi I had to replace both the water and heating elements which was quite easy task. purchased as a pair from Ebay. There is a youtube vid on this. No issues so far with the none genuine elements at half the price