Harrasment and cant proof documentation

They keep on calling me for payments. On start ive made payments but realised they wants me to pay 2 accounts theyve bought from other companies. I am aware of the companies but they cant provide me with paperwork about the companies and still phone me for payments. Im getting fed up with the phone calls and they want to charge me for calls aswell. And when i paid previously my account arrears wasnt dropping. Was still getting higher. Im getting tired of them