Oh god, I don't fancy calling them again! They forwarded me onto about 5 people because they didn't know what a Coaxial cable was!!! and they started getting angry with me because I said I already had an Ethernet... it was awful, if it works I would rather just buy my own cable than talk to them again! I think I already have a splitter it looks similar to this one:
http://homepage.ntlworld.com/altisuk/fm/isolator.jpg
But only has one Coaxial connecting the STB!