Name servers are correct. The person in question is using Windows Vista and their ISP is O2 (The british mobile phone network) She has managed to access the site for short periods and then suddenly she starts getting redirects. It's really odd. I've told her to clear all private data in Firefox except saved password and that hasn't helped. I think the redirect is our old host 110mb.com's advertising page for when a webpage isn't found. But I cannot understand why it might be loading that since the name servers are and have been since signup been setup to use Heliohost.
Hopefully this can be resolved because so far the service has been an incredible jump from the slog of 110mb.