Welcome to the forum Patrick. In the UK we have about 10 dealers. I would start by messaging Kool Classics as they seem to be the most helpful at sourcing parts. https://www.eriba.com/gb/en/service/dealer-search
If you click on the three bars top right corner, next to models, you can access the menu. This will help if you need to go to my next point.
To be assured of a positive result you may however be better off contacting one of the dealers in the Netherlands/Holland. They sell a LOT more Eriba caravans than in the UK. Last summer we visited about 6 dealers. All spoke perfect English and were very helpful.
After a bit of digging you may in fact be in luck with this French supplier. https://retrocaravanstuff.com/collection...ok-handle-latch

Best of luck and let us know how you get on - Colin