I understand your frustration. at the facility I manage, there is a huge wall of windows to let light in, which is great, except it leaked ever since new....after much fighting and arguing, the manufacturer had a third party conduct water tests to help determine the cause. There was a specified pressure, nozzel, and angle, of water to be applied to the exterior. It took these tests to get them to finally pull all the glass and re-install the whole "wall".
I doubt the tests on your trailer will be quite as standardized, but it is a path they must take.
How it all works out the best for YOU when this is done.
Joel and Teresa
2016 Sabre 34TBOK
2006 GMC 3500 CC LB DRW 4X4