never had a absa creditcard but being harrased for

Since 2011 these people have been harrasing me to make payments on a absa creditcard. I have never in my life had a absa creditcard and have asked them for proof of where I signed and what . Supposedly purchased. On numerous accounts I have sent them police statements stating that this isnt my debt as they requested. Now they phone me again saying I have to send police statements again. This had been done many times. I told the lady to stop phoning ive sent them what they asked and this isnt mydebt she responded by saying they will phone me until I pay. Why must I keep on explaining iv. Never had a absacredit card