Bad and Unprofessional Service

I have been getting calls and smss from this law firm claiming that I have an MTN account which I owe and that I need to contact them regarding this matter since I have been avoiding their calls and mind you i know nothing about this st*p** account that they talking about so I decided to WhatsApp them seeking proof of this account and proof of my details but I was rudely dismissed. These people really need to stop harassing us if they cannot even provide a simple proof of one's debt or information linked to whatever account!