It's not the end of the world
I got the Tiscali DNS error page when I was surfing late last night. I fired off an email using the "Contact Us" form (why dial an 0870 number?) and received an apology at 09:53 this morning - i.e. Saturday. I have checked and indeed the page has gone. Since Microsoft hijacks the DNS error page anyway in IE unless you disable this feature, what Tiscali did was meely mildly annoying.
For the record, Tiscali's reliability and speed has been very satisfactory these past few months after a shaky start. And no, I don't work for them.