I send the three validation letters to a collection agency. When I had no response, I sent copies of the letters with the postal receipts to Experian. Now the tradeline shows: "Account information disputed by consumer. (Meets requirement of the Fair Credit Reporting Act.)" Was this notation made by the collection agency or by Experian as a result of my dispute?
File a complaint with the FTC and your state Attorney General. It is likely that the collection agency can't validate the debt.