How can I change the domain name on my InstantSite?

This article applies to 123 Reg InstantSite packages

Unfortunately, due to the nature of the InstantSite package, it is not possible to change the domain name associated with your InstantSite package once the package has been activated.

If you wish to use InstantSite with another domain name, you must purchase an additional package, and cancel the old one if you are finished with it.