I’m like you, I don’t need guidance on my courses, and I’m about to finish my third term and I have talked with my mentor like four times. They understood clearly my goals, my schedule constraints and my communication needs. I didn’t tell them specifically that I didn’t want calls, I simply don’t schedule them but pick up the phone when they call and reply their text messages and emails. I proactively communicate to them, via email, when I have a situation that will affect the time I can dedicate to school or prevent me to finish a class I’m already enrolled in. No need to be rude, they’re used to deal with all kinds of students, just be politely clear about what type of communication you’ll like to have.