Telkom is harassing me

Please someone point me in the right direction Telkom accuse me that I owe them money the saddest part is I never open an contract account with them and now I have send the documents they requested so they can investigate, they requested after I told them I have no knowledge of the account they claim I have . My problem at this point they won’t stop calling asking me to pay the account they are supposedly investigating, someone explain it to me why they calling me if there is a case pending????

where can I take this case I can not stand the harassment I am getting from Telkom