Well the plot thickens, as they say. I went to pick the Lawnmaster mower up after the repairs, and noticed flaking paint on the catcher hook. The chassis had been replaced, but a quick scrape revealed that the rust, dirt etc on the hook plate had been painted over with a spray can. No cleaning no prep just sprayed!
I have left it there, and am getting confusing messages about what they are doing about it, if anything, at this stage.