Damp floor in 2016 in caravan and failed roof stra

My Wife and I part exed our 10 year old bailey olympus caravan in September 2020 for a 4 year old bailey unicorn vigo from a dealer in the North of England. It was sold to us with a full pre delivery inspection and service. On collection of the caravan everything seemed fine apart from they were still replacing an external 240v socket cover then informed us they needed to replace the mains hook up cover but none left in the shop so they would send a couple out to me when back in stock as I said I was happy to fit myself. We then did all the paperwork for the finance company etc. All complete until I asked where my service sheet and damp report were and they advised me they would post out to me, again I didn't see any issue at the time but never received this or the replacement flap even after phoning a number of times. We towed the van to our site where we keep it in storage and used for the next 4 weekends until the second lockdown started in early November. We then winterised not knowing when we would be allowed back which wasn't until 12th April 2021 as we had been in tier 3 then the 3rd national lockdown. We arrived back at the caravan to find our roof strap had failed causing damp and mould in the cupboard above the bed ruining this cupboard. I have temporary applied a plastic sheet strip secured with duck tape to stop the ingress from this. Luckily for us we have an Approved Caravan Technician who has his caravan on our site and does the servicing/repairs to most caravans on our site so we asked him to check our van over to see how far the damp had affected our floor. He carried out a full damp check and found major damp issues in 5 areas of the floor ranging from 30% to 55% in a couple of areas which in his words will affect structural integrity of the van. He then advised us to contact our dealer via letter/email so there is a paper trail and told us to advise the dealer we are offering our Rights to Reject the goods supplied to us as per the 2015 consumer rights act 2015. My first email was over a week ago followed up with a physical letter sent recorded delivery and up to now no reply as yet