Poor service!!!

I have a contract with cell c - *** Don't even know where to start but I'm very much unhappy with the service I got from EDMOND LEBEPE, who happens to be an escalations department consultant. Told me straight He will not be processing any credit application after I was overcharged a penalty for the month of June for my contract were I'd already made a cash payment on the 25th of May were as my debit order date is on the 30th. His argument is that He cannot account for the system mulfunction and this information is confirmed by the bank. I happen to have to understand that January I made a cash payment on the 28th and it reflected on the 29th and I was not debited nor charged a penalty fee but this time I'm charged a penalty fee when I've made a payment 4days prior.. If there's is not rectified I will honestly take further steps..