De*****ing by Le Morgan and mrtr

Collections company from Le Morgan (mrtr) wants me to pay an amount of R1278.38 which I don't know what it is for. They have threatened me with sheriff's if I don't pay them in the next 72 hours. I contacted Le Morgan which confirmed that I don't owe them and they don't know why this company is calling. The last payment was made in June 2021 which the last amount I owed them