AES/PHEAA Debt Collection Complaint

AES/PHEAA Debt collection department,

Non-federal student loan Cont'd attempts collect debt not owed Debt was paid North Carolina

I paid of my - student loan more than two years ago and even received an email congratulating me for paying off my loan. Recently, I began receiving emails from - about my balance being available, but when I logged in to their website, there was no balance. I assumed this was a computer error. However, - apparently has sold my imaginary debt to AES, which now claims my debt is - plus - in unpaid interest. There is no way this is even possible. Ten days ago, I submitted a written request for verification of the debt to AES, at which point they began harassing me with phone calls multiple times a day. Then today I received an email from AES saying my request could not be completed because I never returned their calls. I realize this is for a small amount of money, but it is money that I do not owe, and I have a right to receive written verification of the debt. My credit has already been ruined by student loans and I'm not going to start paying made-up debts that I don't owe.