Bad Customer Service

For 3 weeks now I am trying to get Discovery bank to credit my account with the R1000 I paid the account abut they keep sending me arrears SMS's I spoke to Grace TWICE sent emails of proof of payment. I can't be calling all the time ( about 6x ) and holding on for the machine to go through all the options while I am calling from my mobile phone. this is not on it reflects on my credit score that I want to improve