Continueously wrongfully billes by Telkom

Telkom has started again to bill me wrong...in February 2020 they told me that they have resolve the matter but now they wrongly billed me R590, while they were suppose to credit my acc with R352.06 and my monthly installment is R238.00. Please advice i am enough of this because they are enjoying to receive my call each and everymonth and not resolving my issue.