Hi, Graham. Goodness, that first one could moonlight as old-school 3D. I'm really sorry you're having trouble with your convergence. I may have missed it, but can you just have your seller present the issue for a replacement?Rather than ask directly for a replacement (initially anyway) I will contact the seller and JVC with my photos and see what they say.
I don't think asking for an exchange under these circumstances would be seen as fastidious or analogous to thumbing your nose at anyone. On my monitor (with your convergence adjustment settings), some of the otherwise white characters appear bluish in hue while some appear white in the same screenshot. If that's the case, then pixel adjustment doesn't seem to correctly remedy it.
Is that what you're seeing in person?
Whatever route you decide to take, good luck!