I presume this is Tiscali Homechoice. I can`t see any reason why the D-Link shouldn`t work. I see that Tiscali offers a Netgear router with their package but this shouldn`t make any difference. Tiscali have a helpline 0870 744 2922 (National Rate) and their wireless guide is click here
Other than that we could look at the D-Link settings but try the helpline first.