Computech credit services

This company keeps sending me emails claiming that I owe them when I don't. Now they are sending me emails about a sheriff and that I have to pay them urgently when I have never received any money from them. Honestly this is frustrating and I don't know how to make them stop. Are they even a legal business as I have tried to search for them online but find that it states that they are permanently closed down. Is anybody else experiencing the same problem?