Turns out mine was faulty too! Managed to get my nephew who knows what he's doing with Mac matters to come and look at it and he diagnosed the problem. Local firm - whom I got it from - accepted his word for the troubles and swapped it for a new one.
It's now being recognised by the network but I'm still, alas, having trouble setting it up and feel the instructions of how to do so are nothing like as clear [and simple] as the majority of other Apple manuals and instructions which, generally, are wonderful compared with doing the same sort of thing on a PC.