Debt collection — AMCOL Systems, Inc. (TX)

Debt was paid. XXXX XXXX XXXX ... I needed medical treatment when I first arrived to Texas, went to an emergency facility because I didn't know where else to go ... Received treatment on XX/XX/2017 and paid {$220.00}. I asked if this settles my bill with the nurse, doctor and receptionist and I was told yes. Received a cash receipt. Six months later I began to get bills for {$350.00} and I wrote back stating bill had been paid in full with {$220.00}. Then I started to receive bills for {$150.00}. Now, they have submitted 5his information to a collection company called Amcol. This information is now showing on my credit report. Help?