Ameristar Financial fraudulent? Libertyville, Illinois

I had a truck that was repossessed by ACC in 2007, due to job loss. The account was sold to Ameristar in January of 2008. They have not attempted to make contact with me since then. I have recently made progress in fixing my credit and paying off my debt. In October 2010, Ameristar reported the debt on my credit. I have been trying to contact them since, with no response. Either the number is incorrect (the ones on the credit report are) or there are numbers to what seem to be fictitous people. I have left numerous messages on the 'fictitious' voicemail servers, but have had no response. It does not matter what time of day I call, the results are the same. I am stuck with this on my credit at the most inopportune moment and have no luck in fixing the problem. I am not trying to avoid my debt and still to no avail.