Aggressive Collection agents - Mbd Attorneys & Woolworths

I have been a loyal client with woolworths and have been paying them regularly until I encountered some financial problems whereby they handed me over to the above e attorneys. In the interim I have been retrenched. I advised these collection agents that I would be paying when I was able to. Despite me honoring most of our agreements, I have been harassed for up to 12 calls a day, with rude aggressive attitudes, in particular two agents, with one telling me that he is Mr so & so, and a other female, upon me telling her that I could not make a payment at the time, telling me very aggressively that I took the loan out so my issue is of no concern to her in a shouting tone. Tried calling Woolworths and they just shrug their shoulders