It is a collection agency for a Comcast bill which I have already paid. I do not blame the caller. The problem is that Comcast is a poorly managed compnay which does not have a functional inter-company communication system.
I had moving service, and Comcast made a mistake to treat me as a new customer with a new phone number. In order to fix the mistake, they have to create the third account to transfer the first account, then cancel the second account. The entire process, technical and billing, took two months to settle. I received a bill for the non-existed second account. The billing department told me (when I called them) not to pay since someone is working on it. To be sure, I contacted the service center and also was told they will fix it. Last week, I got the same bill again, now it is an unpaid bill. I decided that I have wasted too much my time and energy, it is not worth to point out how many mistakes they made on the bills of three accounts. I paid over the phone with Comcast rep. I thought it is over. Even I paid for Comcast's mistake, but, I will not deal with them anymore.
Today, I got the collection agency's call. Give Comcast the benefit of the boubt, I will say at least the company does not have a functional communication system.
Now I understand why we need anti-trust law. If a company dominates the market, the service will be poor. I use this site to complain since there is no way I complain on Comcast web page. They even do not reply my e-mail sent to their customer service department.