Failure to debit on set date

I have been in an accident with one of Telesure client, Ive been contacted for statement in 2016 which I did provide. Couple of months later I was called to say I owe R40368.08 worth of damage. I asked to see what was fixed exactly that resulted to such amount. That quote was never sent to me. I contacted my lawyers for advice, we came to an agreement of arranging a certain amount which I did according to what I can afford. The account was going well all this months until Telesure decide to debit my account out of the agreed date. The lady by the name of Rhulani Khoza called me saying I didn't pay, when I become resistance of what she was saying that's when she said it's system error. She couldn't get to agreement with me when I say I can sent my December & January bank statement to prove I had money.

I have no control over Telesure's systems to a point that they send me a letter of default. Is this the right practice or Telesure is taking advantage of consumers? Telesure I need answers urgently.

Regards Frank