I do not think anyone is suggesting fraud or neglect on anyone's part. Here in the US an insurance appraiser is paid by the insurance company and their job is to pay out as little as possible or nothing...... so I put very little reliability in their findings. I had to go through arbitration once after an appraiser was going to give us almost nothing on a claim we won against the appraiser & the insurance company.
Your pictures are not very good so it is hard to tell anything from them..... but again we are not staying what you are saying is incorrect. But it is hard for a manufacturer to fix or pay a claim on an older trailer, let alone one that you were not the original owner. Believe it or not manufactures and insurance companies hear all kinds of stories
Also it is possible that something could have happened (From manufacturers point of view) while the original owner had it and the issue not shown up until now.
Also your date stamp on the pictures is from over a year ago. Not a good idea to not have the correct date if it happened in 2015 when dealing in the legal arena they will claim it happened in 2014 and you waited a year........ since that is what you date stamp says.........
Good Luck !!