ELDDIS 2010 AUTOQUEST ALLOY CORROSION & WOOD ROT

Hi there, any members out there that can offer advice or further action? I could take or indeed, suffering the same corrosion issues on a relativley new motorhome?. My recently purchased £26,000 2010 Elddis Autoquest model 10,000miles only,no winter use. Totally mint looking but due to 1 missed habitation check this year and non last transfer of  5 yr warranty, Elddis will not honour any warranty or repair. O/S lower quater panel water ingress from inner wheelarch from poor design build from the factory.. 3 years old and rotten! Horrific on a 3 yr old! Elddis reaction to photos was negative!.............Not good enough.......