Unpaid credit card

I have a credit card with Capitec bank and they deduct their money every 25th of the month but for May month they did not deduct and I only noticed that after I received an sms from them stating that they did not get the payment but there was funds on my account. few days later I received a call from a guy and I made an agreement that they must do a double deduction on the 25th of June ,same thing happend money did not go of and now they are harassing me with calls. On the 7 July I received a call from Yolanda and I asked her if she can access my bank statement to check if there is funds on my account and she said yes there is funds ,so my question is who's fault is it if they did not deduct the money and what about my credit profile ,I asked her to escalate the matter but up until today I haven't received any feedback instead Ntomby phoned me again..how do I deal with this issue?