If I signed a rental lease at the age of 17 and terminated the lease early am I still responsible?

I signed a one year rental lease at the age of 17 and moved out early. The rental company filed a claim with a debt collection company and the debt collection company contacted me about fees due for breaking the lease. I told the man with the debt collection company that I was under the age of 18 at the time of signing he asked me to fax a copy of my drivers license to him for proof. He then contacted me and told me that the claim will be dropped since I was a minor at the time of signing. Now 7 years later I did a credit report online and that claim was still there. I contacted the same debt collection company and the man there told me all the information I just previously stated was in the notes on my account but I was still responsible for the debt even though a former employee of his company told me I wasn't. He said the man was mistaken and made a mistake but I was still going to be held accountable. If an employee if his company made the mistake and told me everything was resolved and have not tried to contact me since then, how is that my fault.