Being called stupid by a shop assistant

I walked into Vodacom Tubatse crossing earlier today to pay for an account. I was received by a consultant named Tumelo, he asked me what I needed assistance and I told him I was there to pay for an account...he asked me if I was going to pay with cash or with card and I told him I was going to use card. He led me to a self service machine and said I could pay there, he stood next me to assist me but I was able to get around the machine to a certain point and this is the point were I was insulted to my core. As I was punching in the cellphone number of the account I wanted to pay, I didn't realise that the number was censored and not visible so I proceeded to submit, this guy Tumelo does a shocked expression and I asked him what's wrong? His response " Be ke re o hlalifile mara kea bona gore be ke le wrong( I thought you're smart but I was wrong)" I gasped and I thought I was hearing him wrong and he repeated it again. I asked him if he just called me stupid and he laughed. I told him it was very unprofessional, extremely rude and wild that he'd say that to a customer...he defended himself by saying "batho a re swane, o mongwe nne a ka se tjeye the way I took it" . I couldn't even pay the account because of how hurt, shocked and disturbed I was by his behavior...I just stood there frozen not knowing what to do. I asked to see the manager Angel, who did not even care to hear what I had to say, after being called multiple times..which showed me that there was no sense of urgency from this team and staff could behave however they wanted because it is allowed and has no consequences.