Financial Credit Services trying to collect on an account that isn't mine Ripoff Palatine Illinois

I received a letter from this company on August 25, 2007. It stated they have an outstanding debt of over $4,000 that they are trying to collect on behalf of Chemical Bank, a bank I have never heard of. On the 26th of August, I called the number on this letter and they claim that this account was opened in 1995, I have never had a credit card up until 6 months ago because I have no job, so how would I obtain a credit card? The letter from this place is very fishy, it says I have 30 days to dispute this debt, and if I do not dispute it, they will assume it is valid, what do they mean by assume it is valid, I have never seen a bill worded this way, they have no proof of a signed credit application or anything, and said they could not send me any of that. They claim this account has been opened for 12 years but yet this is the first I have heard of it. They even claim they have received a few payments a long time ago. My daughter ran all 3 of my credit reports and this account is nowhere on there, if it past due 12 years it should light up like a christmas tree on my credit report. They will have to take me to court with some proof of this one because I do not have a credit card from the year 1995.

Louise
biloxi, Mississippi
U.S.A.