very very bad attitude and insults from Branch manager

I have just been insulted by a Telkom Southgate branch female manager, she gave me a very very bad attitude and insults in front of other customers just because i did not have my proof of address for sim swap, she did not even care about my frustrations as a customer, this was the baddest customer experience i have ever had to go through, she made me feel less of a person right in front of other customers, i really need help as to where can i report this matter because i strongly feel like she needs to be reprimanded in a disciplinary action and until that happens i am going to add a review about my bad customer experience and the insults i got from that branch manager, please kindly advise as to where can i send an official email complaint about this because i can not be disrespected, insulted and embarrassed like this as a customer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!