opps, we're moving away from the topic.. have you managed to get sorted laurajay? its always good to know the outcome
Well I solved the problem by fashioning an object from an old box of technic lego and sticks from a couple of defrosted ice lollies
Or back in the real world, this morning the temp in the bottom shelves were only just above freezing and heading north. I managed to source a service manual of one of the newer Samsung models which at least gave me a fair idea of how to take things apart safely and put them back together. So I took the covers off, defrosted the ice build-up and put things back. Seems to have bought me a few days to solve the underlying problem as things are back to how they were with only the shelves remaining above freezing.
Pretty confident I could change some components myself if necessary (have sent you an email Bryan) but would actually prefer getting an engineer in tbh because things are getting desperate here, only so many defrosted sprouts I can eat. Having problems getting a recommendation for anyone local at the moment, so tinkering myself based on the suggestions here may be the next step.