my email used for another client - no resolution

MBD Debt collectors have been using my email address and harassing me with letters to pay my woolworths credit card. I do not have a woolworths credit card, and the id number needed to open the document in the email, is not my id number. i have called twice, both times, they said my email was removed from their system. I still received an email, the 3rd time i called, they want a reference number on the document, which i cannot open, i just get blatantly told, they cannot help me. Surely this goes against the PoPi act. I want my email removed from your system immediatley.