Lol...
Actually I found the process relatively simple, but maybe I just got used to the way bureaucracies work elsewhere? One e-mail to BMW, a scan of my V5 and BMW's letter, registration with TFL and completion of their online form and press enter. 7 days later I had a reply confirming I'm ULEZ exempt. No money changed hands and the whole process was less than an hour of my time if I'm honest.