viperdns

My Safari browser in my iPad has been hijacked by a website: viperdns.com

It simply does not allow me to use other websites. Once I type or click on favourites its URL takes over and gets the page on screen. I have tried blocking it, but then I only get to the screen telling me it is blocked "Restricted Site". I have cleared "History and Website Data". Some websites work, for example none of the BBC do but then others open without that problem when I access them from the "Favourites" buttons.

How can I get rid of this problem?😕