Harassment by Credit Intel

Ooooh please help. This company has been harassing me with legal actions, sheriff and a whole lot of intimidating emails and messages. I really do not remember utilising the services of their client whom they call Computech. I've requested them since last year to send a contract I signed or a voice agreement made with this Computech, they failed to do so. I'm so tired of their daily harassment. What should I do?