Given that I’ve helped hundreds of people write out deeds poll for free, but there are companies who try to sell basically the same service for around £30, it’s my feeling that most of these companies are ripping people off.

The one you linked to can’t spell “United Kingdom”, by the way, and doesn’t know what the plural of “copy” is, which doesn’t give me a lot of faith in them. They also seem inconsistent in their pricing structure, depending on which page you look at. I mention this just in case the site is yours.