It took me forever to make the appointment online but I was able to do it. Try first thing in the morning, you may have more luck than if you try to do it in the afternoon. I scored one a month away, but at a location I wanted, and it actually went swimmingly (I was in and out in 10 minutes). Never managed to figure out the phone (unlike 2 years ago), and my e-mail just produced a response of 'new slots are added daily, keep trying' basically.