Van issues since new - Where do I stand?

I took delivery of my first, brand new, coach built motorhome in November 2016 from a franchise dealer - the initial snagging looked at several minor issues and two others that seem more significant:-

1. THE HAB DOOR - only closed properly after 3 or 4 hefty slams and occasionally didn't catch at all. The initial door lock/catch replacement made no difference, and neither did the dealer's idea to attempt to realign the door by  sticking  a small block on the bottom of the door and another on the door jam to hold the door slightly apart - The only effect was for it to allow water and condensation to accumulate at the bottom of the door on the inside of the van!

2. THE CONDENSATION - On the first occasion we stayed in the van with the heating on we noticed that water/condensation occurred on one side of the van behind the seating cushions.  This was enough to form a puddle on top of one of the locker/seats. They dealer  took the van in and told me they would fix this. Unfortunately, as we discovered on the next occasion we used the heating, the identical  issue still occurs. 

The van is now back with the dealer who has told me that after more work "the condensation is 80% cured" and if I give permission for them to build in a 1 inch spacer between the seat cushion, that I won't see condensation.

Although my van is now 4 months beyond the 1 year manufacturer's warranty period, these are problems that have existed and been treated unsuceesfully by the dealer since new. i suspect   that the condensation issue is only being masked - and that actually there is a manufacturing /insulation issue in the wall cavity (signs of condensation can be seen on the outside of the van too when the heating is on!) I'm concerned that the fix they are suggesting may affect any future sale/price of the van and for any  effect on the longevity of the van's life.

The Hab door is still under review as it appears the manufacturer and the dealer seem to be in disagreement over replacement of the door - The manufacturer's say it should be adjustable to make it close properly and be water tight too - but the dealer says they tried everything! 

I bought this particular van because it was promoted  as an all-year round van with dampness warranty. I'm worried for my £45,000 investment that has only done 4500 (700 of those miles due to the return journeys to the dealer!)

The dealer is asking for my permission to go ahead with the "spacer" work - I don't really know if I should just accept it - or if I should be asking for a different less bespoke solution - or even a new replacement van.

I have many friends who have provided "opinions" on what i should do but what i'm really hoping for is some "PROFESSIONAL" / KNOWLEDGABLE ADVICE if anyone can oblige please?

Thanks for considering