Breach of trust

So, my girlfriend and my mother went to Tymebank to open an account for my girlfriend, i was working and could not take her. Later that day my girlfriend got a message from an unknown number (it was the banker that assisted with opening her account) he said that if she has any questions, she can ask him. She did not respond to his message. He sent another message asking if he can give her a compliment. So she just responded by sending a question mark. He sent a message saying she is very beautiful. He followed with another message saying that he can see she is in a relationship but would still like to chat with her. She then told him politely no. Now, what my girlfriend and I don't like about what happened is the fact that he got her number from the Tymebank system without her approval and used it in this manner. This is highly unprofessional in my opinion. Tymebank Mokopane is the bank in question.