Payfast debiting from account without authorisation!!!

Payfast is dangerous! Not only do they have rude customer service agents but I have now had two un-authorised debits from my account over the last two months. The agent I spoke to was not willing to listen and refused to accept responsibility for the transactions but it is their system and the terms of the billing cycle were not explained nor signed off on. SHOW ME WHERE I SIGNED TO LET YOU DEBIT ME FOR NO REASON!