<human>: Hello, I have a question about a past due account on my credit report. 

Long story short, a few years ago I let a few credits cards go bad, but I have since paid them all off. 

One account (a Chase credit card) I paid through a debt collector about a year ago and it still hasn't shown Paid in my credit report. I filled claims with the credit agency's and they declined my claim because on my pay off letter it shows National Bank of Omaha with a different  account number from my Chase account. When I was contacted by the collection agency they said Chase sold my debt to National Bank of Omaha and they bought my debt from them. 

Yesterday I called to try to get this cleared up, but the collection agency says they can only provide me letter saying the NBOFO debt was paid. I called NBOFO and they have no record of me. I called Chase and they still claim I owe them money. So, when I called the debt collectors they say nothing about Chase and that I owed NBOFO money. 

I'm completely lost and don't know what to do next. Can someone please help me?

Could you distill the essence of the text into 1-3 sentences?
<bot>: I paid a debt collector on a Chase credit card, but I paid National Bank of Omaha (who I was told owned my debt).  Chase is now stating I owe them the money I paid.