Webasto will give you contact details.
Be prepared for a huge bill. Mine needed a new control board. Tiny board with few components on it was $600. I did most of the work getting it out. Agent in Adelaide supplied and fitted the board and was so embarrassed by the price that he didn't charge for labour. (which was just as well because he stuffed it up and I had to pull it out again and fix his mistake)
Never again will I buy webasto products
Spoke to a webasto agent at camping show melb and he doesn't know anyone that services a webasto diesal cooktop !! apparently no authorised technicians around any more !!!!!!
straight from the horses mouth ... shouldn't be selling them if theres no authorised service agents around disgraceful !!