I'm hoping this won't be the case. It doesn't take much for me to jump brands. As much as I love the D750 it doesn't take much to pee me off when it comes to lousy customer service.
Whoa there, cowboy!
I might have been the first Nikonite who experienced repeated D600 shutter problems after it was replaced. There were a few others who had theirs replaced and didn't experience the oil/dust issue to the extent I did. Plus Nikon scratched my sensor during the first shutter replacement. I never heard of anyone else who experienced that problem. One sensor replacement and two shutter replacements left me no better than when the problem first arose.
By the third time my body was sent in for repair, other Nikonites began experiencing problems after their first shutter replacement. Nikon has a New York based office. And New York has one of those 3-strikes laws. I let my fingers doing the walking across the internet and found the name of the law (the name eludes me now, but I mentioned it here back then). As far as I know, I was the only person to get a refund. Everyone else got a replacement.
So don't worry. Once they admitted the D600 problem AND once they came up with a solution, their customer service got much better. Even with all I went through, I'm still a Nikon fan. Granted, it's not fun DURING the process, but I have no doubt your issue will be resolved.