Cingular Wireless put a bill that was resolved 5 years ago into collections, won't remove from credit report Internet

Over 5 years ago Cingular Wireless agreed to take back my phone and cancel my plan once it was discovered that they did not provide any service in the primary location in which I was using the phone.

They told me my account was resolved and no further action was required.

They then filed a bill with a collection agency. They have refused to remove this from my credit report, despite the fact that they resolved the matter, and the bill, over 5 years ago.

Alexandra
San Anselmo, California
U.S.A.