Getting harrassed by a girl I went on one date with. Help plz?

Ok so some of you know me. I'll be an MD in the US in a few months. Anyway I was shooting the shit at the local university about 6 months ago talking to some girls and I started talking to this overweight (not obese though... Fuckable, basically) girl. I got her number and we met up one day. My idea of a "date" is sitting in a study room playing guitar basically showing off and then trying to make out. So that's what I did. I offered for her to share the piano bench with me. She declined, and left shortly thereafter. I thought, oh well I wasn't really that attracted to this girl anyway. who cares.

Fast forward a few days later I'm shooting the shit at the same spot again and I meet this really hot chinese girl. We hit it off, but I notice that the fat girl is there too, watching from a distance. I could care less, and eventually I leave with this hot Asian girl. Ever since then this fat girl has been blowing up my phone trying to meet with me again. I'm not interested anymore because she's not that hot and wasn't very receptive when we met up. I've tried to drop not so subtle hints that I'm not interested but she just won't go away. She keeps calling and texting and is basically harrassing me at this point. It's been months... I'm not an asshole, and I don't want to be rude but what should I do? Whats the best way to get rid of this girl? Advice plz?

Also if you think this is the wrong sub, plz suggest where I should post this. Thanks assholes lol

EDIT: Btw, being a complete dick or just plain blocking her could really backfire since I pretty much always go to the university for one thing or another. I think she works there because she always seems to find me when I'm on campus..... It's wierd......