Truworths please just stop

truworths are continually calling and messaging me for non existent debt. Its got so bad i no longer answer my phone. I do not have a truworths account and have never in my life bought anything from truworths. If i block their number then they call or message from another number. Today so far 5 calls and a message demanding payment. I have answered their messages and mailed their customer service to try to get it to stop to no avail. Please stop harassing me, stop calling me, stop messaging me. You have the wrong number and my name is not Sikko nor do i know anyone called Sikko