This company? appears to be a scam


http://www.xtrememiners.net/

Based in Germany. It is, apparently, a legal requirement in Germany to have a contact phone number and a tax file on business web sites.
Company address is bogus.
Phone conversations are apparently being done through VOIP and are routed from Hong Kong / China via the USA.
Email responses are 6 to 8 hours out of sync with Euro times.