Yeah, I suppose I'll contact customer service and see if they can get it sorted, or swap the code for one that actually lets me upgrade my account. It's kind of crazy that they wouldn't, you know... warn you about any of this in advance, but I can't say I'm entirely surprised about anything SE anymore. What's the best way to get an answer from support in y'all's experience? I suspect it'll be another odyssey to find a way to contact them directly using this labyrinthine website.