I've emailed Nikon's MD previously about the ongoing AF problems and I didn't get a response from him, just some manager at the service dept that said he'd had the message passed onto him. I did ask then if they'd consider sending a replacement as it'd already been in about four times, but they totally ignored it and didn't even bring it up. So I doubt they'll replace it this time either.
I won't be switching back to Canon as never been a Canon user but I have been seriously contemplating it over the past couple of weeks as some will know, it's only the price of the 5D4 that's stopping me. I should be able to replace my glass for used Canon glass for roughly the same price, it's just the body price difference