Brutally Corrup/ ****/ *****!

I was at work one day when a payment showed with sms. I went to the bank and they showed me my card number was cloned and used with a online purchase. I don't authorize anything. Until that day, I never even heard of them. Now I keep getting emails of them saying they are going to take legal actions if I don't pay R1900. If I try to call them, I don't ever get any answer. I'm really getting sick of this ********** harassing me. If a request proof that I asked for a service or agreed to anything, they don't answer me.