I don't like him, but he is always calling and texting, which is very annoying. What should I do?

You politely answer the short message he sent you, and you politely answer him when he talks to you, so that he knows that there is a distance between you and him, and this distance cannot be approached. If he really pesters you for a semester, on the other hand, he really likes you because he wants to take action to get your heart in a way that suits him.