You can get the bits that hold the freezer door in place from camping shops for about £10. It's a spring mechanism that keeps the door shut. Not sure which bit has broken off yours, but if the freezer door is completely free from the fridge then take it to a camping shop and ask them.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.