Just adding this here to give an update, and for the record
Yesterday I did 'unsnake' the old cord and EVSE and took them back to the dealer, whom I had previously contacted. Amazingly, and to my pleasant surprise, the whole transaction went very smoothly and quickly. He came out with the 2015 EVSE that got misplaced somehow (it should have been in/with my car), and we exchanged EVSEs in the zip-tight bags that they came in. It took all of five minutes and we left agreeing that we would have to work with Nissan to get the old one back to them and have my account credited (more specifically, just have the erroneous charges removed).
The only problem with it all going so smoothly and quickly is that I didn't think to get anything in writing (again! Grr..
). I did call NMAC and let them know, however. (Even though I called just
after the 'old lease' department closed, I had another service rep add the pertinent facts/notes to my account. I will follow up first thing on Monday.) I also texted a few people about what happened, will email the salesman a request for an email receipt, and I am writing it here, so I do/will have some written record of what happened. I'm 90+ percent confident that it will all be resolved amicably now -- it's just a matter of time. It would be great if it could be done in time to consider it an early Xmas present!