Treated like a ******** for telling them not to deduct early for December

I am utterly disgusted about the manner in which I was treated by your call center agents who are unprofessional and completely and utterly useless. When I app**** for the loan, I indicated that the instalment date should be on the 25th and yet last month you tried to deduct before that date - resulting in me having to pay banking fees for 4 failed attempts. Today I got an SMS stating that the December instalment will be deducted on the 18th December. I only get paid on the 25th. I called your call center to explain this to the agent, who treated me like a ********, stating that par 4.1.3 of your T&C allows them to deduct early. When I tried to explain that this paragraph states "may be deducted earlier" and does not state "WILL be deducted earlier" and that there's a difference between MAY and WILL, she told me to make sure I have sufficient money or Capfin will "monitor my account" and deduct until there is money. This is unfair practice and already cost me unneccesary bank charges last month and she simply told me it's not her problem and put the phone down. I called back and spoke to an equally useless call center agent who reiterated the same thing and refused to give me a reference for the call; telling me there's nothing she can do and her manager will tell me the same thing. What kind of service is this? Your T&C does NOT state NOR give you authority to deduct BEFORE the instalment date. The T&C states that it may (MAY) deduct earlier. MAY is not carved in stone and seeing that I did you a courtesy to call and say that I won't have money in my account until the 25th, I am treated like garbage. I did not give you consent to change the deduction date and you are negatively impacting me!!! You want to take my last R500 that has to last me until the 25th. Utterly disgusting treatment of clients.