Curing leaks and Straightening a sagging roof

Lunar warranty was insurance based after the 6th year. The insurance part is still valid in your name provided annual service has been done. Lunar did publish that they would honour the vans sold from (I think) 2017 if the dealership was still part of the network.

Regarding the sagging roof of your Lunar caravan. Unfortunately it is a feature of caravans made by Lunar in the last few years before they went bust. I suspect that making the caravans wider and fitting a very heavy central skylight  lengthways has contributed to this problem.  I also suspect that previous owners and service personnel have unwisely caused some of the roof sag when attending to routine resealing of roof straps and skylights. And real problem it is because it allows water to pool on the roof which depending on the degree of sag can cause the pooled water to oveflow the skylight rim and leak I to the caravan. Pooled of water can eventually leak though the roof straps where the front and back panels join to the roof (my earlier lunar caravan had an aluminium roof that  joined the front end back panels just above the window level rather than on the flat roof itself and our roof never leaked in the 10 years we had the caravan)

I have seen one owner who has used two square section steel roof supports fixed to the sidewalks and concealled in a plastic moulding. He claims to have reduced the sag to just the odd mm. It looks like a complicated job involving making robust anchors on the sidewalks, cutting holes in the cupboard fronts, jacking the steal supports up to reduce the sag then securing the supports. He has done a very good job which unless you look inside the cupboards all you can see is the white plastic moulding across the roof of the caravan. I am tempted to try something similar but less intrusive by adding further support which I would screw to existing roof timbers. This however really needs some serious  thinking out.

Currently my caravan is in storage together with its roof cover, stored  front down with one wheel on a 2"plank of wood to help water to drain off the roof. I have also positioned two drywall supports in the caravan which I have set  to provide gently assistance to the roof to try to limit the degree of sag during the winter storage period and possibly reduce the extent it might sag in the future.