Merchants and Professional Bureau, Inc. Debt Collection Complaint

Merchants and Professional Bureau, Inc. Debt collection department,

Other (i.e. phone, health club, etc.) Cont'd attempts collect debt not owed Debt was paid Texas

In - I had an over due electric bill of $430.00. I was incarcerated until -. The billed was turned over to a collection agency. I was paroled -/-/-. I went to have my electric turned back on and was informed I owed them $430.00 for the past due bill. I paid the $430.00 directly to the electric company so they would turn my electric back on. I checked my credit report in - and found that the collection for the past due bill was on my credit report from a collection agency. I submitted a dispute via - with experian. I got a letter from the collection agency about my dispute, they said it was a valid debt that I had to pay. What do I do now?