Strange Problem with a new connection

Hi ,I tried hooking up my brothers talk talk broadband today with the supplied modem via the ethernet connection but it would not connect. Tried my own netgear router from home and it connected no problem so went to the help section on the talk talk site got all the details for the modem to make it work with vista and tried again but the thing refuses to hook up. Seeing as how my router worked and all the settings are the same for both is it likely that the modem is faulty? and if so how would he go about getting talk talk to replace it?