Annoys the hell out of me when you buy something brand new and feel like you find the issues they should have sorted when trialling before production. I say this as I’ve just bent the stupid tailgate retaining lever on my newish IW tipper

Yep been there, my gh1054 was delivered with the wrong skids, so they changed them for the "correct" ones which were also partly wrong and never rectified. The fastening nut that holds the skids up is also terrible it constantly loosens so has to be done up with a set of grips, can't tap them with a hammer as the lever snaps.
My Brian James tipper was also plagued with a few shitty problems that should have never been, was their first design and came with sides that didn't touch the bed and I don't mean a mm or two short was best part of 10mm. They even said at the time that's how it's designed and should be, I did say if I put sand on the trailer it will be all gone by the time I get to my destination. Took it to their hq and their first fix was to try and bend the bed up, when they realised that wouldn't work they designed new sides. I had the trailer while they were designing/building and were going to swap it for a new one, I spent the next few days gingerly trying to not scuff up the one I had but then said to them if they gave me the mesh sides I'll keep the one I have and just get the sides fitted to this one rather than them have a used trailer on their hands. They agreed and went to get the new sides and the mesh kit fitted. The mesh sides were straight forward as they didn't fit and the trailer needed a slight "adjustment" which again was bending with a forklift