I'm keen to join advertising & media sector, which is the best course to do for a B.Com graduate with almost 3-year of experience in BPO?

Hi Vanish, You can pursue a postgraduate Diploma in mass communication or a specialised Diploma in advertising in order to get into advertising sector. Any graduate can pursue this course. You can find the best colleges for advertising on this webpage: https://www.shiksha.com/mass-communication-me