CBE Contacted me in a letter dated 03/25/2016 re: a medical bill that was paid off with original creditor on 8/8/2015 Cedar Falls Iowa

I am SO GLAD that I keep ALL financial records for about 7 years because I still have the records that I paid off my husband's medical bill with UAMS to UAMS DIRECTLY as of 8/8/2015.  I just got a letter from CBE Group dated 3/25/2016 after NOT getting ANY letters from them for OVER A YEAR because UAMS agreed with us to take back the billing from CBE Group until the bill was fully paid off which it was as of 8/8/2015.  I sent back the proof that the bill has been fully paid off along with a notice that CBE Group HAS NO RIGHT TO COLLECTING ON THIS ACCOUNT because we ONLY deal with ORIGINAL CREDITORS and because THE ACCOUNT HAS BEEN FULLY PAID OFF AS OF 8/8/2015.  Talk about an unbusinesslike company!