Blake and Associates Harassment!

Blake and Associates consistently harassing me for payment from Telkom. I have been issued statement from Telkom that I do not owe them a single cent. Blake and Associates however keep on phoning me and to date (6 months down the line) still have not issued me with a proof of statement. Telkom also has no record of handing over my account to them!!! Also keep asking for my date of birth, ID etc. Which they should have if I have been handed over to them by Telkom, as Telkom has all my details. Keep on asking them to mail me to no avail. Asked them then for their email address and it comes back as non-deliverable??? Spoke to one of their "consultants" and they spell their email address "center" as "cencer" LOL.