A student contacted me on my personal phone to help him with the course. What should I do?

s0natagrl

So today a person who had just purchased my course somehow found my personal phone number and wrote me to help him with the course. I invited him to do it and if he had any questions to contact me through Udemy that I would be happy to answer his questions but he kept writing and even sending me screenshots asking questions. I repeated kindly the same response as before hoping he doesn't get mad at me and leave me a bad review. My question is if anyone has advice about what to do in this case? Thank you!