Debit order PTT Marketing

I received an e.mail from Absa, where I have a small savings account. The sms requested me to fund my account as a debit order of R89.00 was to be deducted in favour of PTT Marketing. I have never heard of PTT marketing and have definitely not authorised them to take money out of my account. After several phone calls, first to Absa, who informed me that a company called Paytoza handles all their debit orders, and then to Paytoza, I was given a contact number for PTT Marketing. Lo and behold, it was a cell phone number. I phoned and a lady answered in an African language, giving me another cell phone number to phone, which I promptly did. This number went straight to voice mail. What I want to know is, how can Absa or Paytoza accept a debit order on my account without authorization from myself or do they just accept any old signature?