AmeriCollect Debt Collection Complaint

AmeriCollect Debt collection department,

Medical Cont'd attempts collect debt not owed Debt was paid Wisconsin

I have a bill from - for an xray done on my son that has been paid in full ( proof of payment attached ). They referred me to a collection agency : Americollect Collections. I disputed the debt within thirty days of getting the collection notice and sent proof of payment to the collection agency. I have received no further written communication from the collection agency. I have called them and they indicate that I still owe the debt per -. The bill was paid in full on -/-/2015 and they are still engaged in collection activities as of -/-/2015.