Refuse to assist to fix account

I have made a payment on the 29 th of march n2019 of R640 and for some reason they cannot find my payment and I have sent email after email to have this sorted out and no one gets back to me to help me or when I phone they say they will escalate the matter and still no feedback. I have now been penalized for late payment and listed as a slow payer on ITC and still no one gets back to me. Is there anyone out there that can assist me to help me sort out my account with them. I get then debitted an amount not even close to the outstanding and when I phone there customer care number they just cut me off and say there is no records or comments made on my account

How can a big company not care to sort out accounts after I have sent 5 emails on a daily basis