Sorry about you lens. With all of the problems your luck HAS to be getting better, doesn't it?
Man wev, this must be like a very long bad dream. I hope they do right by you with the Tamron. If you did just wear it out you should get the new model one at no charge and they should just put you on the payroll as a real world cycle tester for their long lenses. Then just clock your cycles and if it survives a year of your use it has to be good...
Really sorry about the D500 hope they don't leave you hanging this time and you get it back soon.