I had the same problem with PredictoMobile and TMobile that many others have had and I read the responses by PredictoMobile customer service.
I didn't catch the billings on one of my company's corporate phones for several months because no one else is authorized to change phone services. When I did see the charges, I contacted T-Mobile and they agreed to remove the charges going back three months and gave me the number for contacting PredictoMobile. I contacted PredictoMobile and they agreed to end my services and they gave me the same story as Customer Service gives on this website.
They said that even though they couldn't give me the name of anyone associated with this account, that someone with access to the phone had responded to one of their ads and they sent a text message to the phone on July 8, 2008. With a PIN that was sent in the text message, this unkown person entered the PredictoMobile website and entered the PIN to sign up for the service. The only problem with this scenario is that according to T-Mobile there was no text message of any kind sent to this phone on July 8th or for that matter within 10 days following July 8th. No text message means no PIN which points to a scam in my book.
I am also frustrated with T-Mobile after reading this site because they had to have known of complaints about PredictoMobile at least as far back as July but it appears they never made an effort to address the problem and in fact when I called today they said that they were going to "black list" the company. T-Mobile why not try to protect your customers? And while the service is apparently ended now, the company is still out 3 or 4 months payments at $9.99/month. A cheap lesson I guess but $40 from a million people makes someone really rich.