I feel your pain.
Fundamentally the panels on elddis caravan's are not fit for purpose and/or the frame underneath is exerting excess stress on the panels due to incorrect fitting and/or the internal frame is too big. They ought not to be cracking (even when stored in a barn or whatever) but there are so many instances of Elddis panel cracks out there - recorded on forums etc .
If your caravan was bought new and is less than 6 yrs old then one option is to get an Expert Report done on the caravan to verify the "cause of the cracks" and the remedy required to fix the fault.
Dave Shaw (of Chesterfiled;
leisurevehicle@gmail.com) is excellent for this job. He is an independent caravan consultant & writes these reports all the time incl on the dreaded Elddis panel cracks; reports cost approx £3-400. He writes his reports in a way that is acceptable should you need to follow the matter up as small court claim, meaning his report is powerful evidence that a judge will accept.
If the report points to a manufacturing defect then you have the ammunition needed to take this further. My advice would then be to join Which?Legal (at small monthly cost) and follow their advice. They have /and are dealing with caravan cases; you could even ask for Paula Oligbo - she is a qualified solicitor at Which Legal and has experience of such caravan cases.
Don't be fobbed off by dealers/ elddis etc. especially you have the protection of the consumer rights act 2015 and a strongly worded, clear Expert Report.
Elddis needs to get its house in order re: cracking panels- or they may not have any customers left who are willing to risk buying their products
Panels come in different grades and I wonder if Elddis is just buying the cheapest on the market.