First off, I'm happy to say this was finally resolved after more than 7 attempts.
Some advice: I don't believe anyone on this thread has recently received a reply from Maxwell or any other "private" message, so don't bother waiting.
You need to follow the instructions here
https://support.office.com/en-us/article/Special-offer-for-customers-with-Office-2016-and-Office-2013-standalone-applications-c32e3cad-e935-4163-a44f-50d896e10bbc
When you get a representative, paste this:
I'm looking to upgrade my Visio 2013 product to Visio 2016 as per Microsoft's special offer, https://support.office.com/en-us/article/Special-offer-for-customers-with-Office-2016-and-Office-2013-standalone-applications-c32e3cad-e935-4163-a44f-50d896e10bbc
I tried SEVEN times, and every representative had a different approach and response. I finally got someone who "escalated" the issue. After some e-mail interaction I actually got a call back from someone who knew what they were doing, and got my Visio
2016 license set up. A BIG problem is if you don't have your software associated with a Microsoft account. **If you installed 2013 using a product key, they absolutely can't help you.**You need to have your product key associated with your Microsoft account.
To add your Visio 2013 product key to your account: https://setup.office.com/ (this is the step the representatives don't seem to know)
To check Product Keys associated with Microsoft Account:
office.com/myaccount (https://stores.office.com/myaccount/home.aspx)
Good luck! And if it doesn't work the first time, keep reconnecting to a new rep and try again... and again... and again.
**If a representative tells you they need to transfer you anywhere, forget it and start over.**They don't keep records of prior sessions, obviously.