Have receipt for Co-Pay they said I owe. Spoke wi...

Have receipt for Co-Pay they said I owe. Spoke with medical provider, they said there is no balance due. Overton Russel Doerr still claims that the debt is valid, and that I must pay them, or I will continue to receive harassing phone calls. I HAVE A RECEIPT, they said it doesn't matter.. Pay or ruin your credit, my choice. Its a $20 co-pay that I have a receipt for. They literally stated that it does not matter, and that if I don't pay, they will continue to "harass" me. They actually used that term.