I'm an iOS developer and try to upgrade every year using the Apple upgrade plan. Last year I couldn't. Their website just wouldn't let me, with an unspecified

I'm an iOS developer and try to upgrade every year using the Apple upgrade plan. Last year I couldn't. Their website just wouldn't let me, with an unspecified error. Other people with similar errors online found no way of fixing it, even after talking to customer service. It's possible I could have resolved the issue with a phone call, but instead I just dealt with having the phone a little longer. Now I'll own it and have another test device.