Terrible customer service

I paid my account the total balance on eft on the 15 May 2020. 27 May I sent an email to enquire and was told to send proof of payment and they will trace payment. To date the payment has not been traced. Their consultants call me to remind me to pay, I get SMS's reminding me to pay. I sent proof of payment to all people who called me and no one bothers to come back to me.