Just received an email from Automattic | WordPress.com.
I just wanted to send you an update regarding your report that you have been unable to update the name servers for your domain. We have been working with our domain provider Wild West Domains on this problem and they have been trying to get it fixed. They've told me that there is an update ready to go, and it should get deployed some time today (hopefully sooner rather than later!).
I'm very sorry for the inconvenience, and we will send you another update as soon as we have more information or when we can confirm the problem has been fixed.
Let's see what they mean by "today"...