Nimble group call center agents who are rude

I received a call from this number this morning *** the agent name is Thembakazi. She calls me and asks me to confirm my date of birth in which I did. She then proceeded to ask me if I am aware that I owe mtn a certain amount, and I tell her that I'm not aware taking into consideration that I paid mtn everything that I owed them, she then says I am making you aware that you owe, I tell her that I don't yoh the agent swore at me then hang up. Is that how they are trained at the call centers to swear at us? And this is not the first time I've been swore at by nimble group call center agents. I paid up my account with mtn so why am I being disrespected by people who don't even know me. Nimble please make sure you hire people who know how to communicate with people, I myself work as I consultant but I would never swear at my customers no matter the miscommunication, I'm so super angry right now. This person calls me and I am not feeling well 😕