Collections Issue

I talked to a few Reps about 7 months ago to resolve my account balance that appeared on my credit report 3 years after I cancelled my Service, before moving to the UK for the military. I never received a bill and thought I had paid off in full. They sent me a new bill, asked my to review it, and that they would have the hit removed from my credit report. I got the bill a week later, then paid it off straight to ATT. When I called back they put a note on my account of everything that happened and told me it will be removed from my credit report. The problem I'm having is that it's now 7 months later and it still shows on my credit report as a negative collection. It shows I owed 178 but the balance is now 0, which is fine...but it's still on my report! It hasent been removed and it's hurting my score greatly. How can I get this finally removed?? Thanks.