Spanish Vocabulary

I know that SHUT UP is not a Spanish phrase so I say it quietly in English out of the corner of my mouth at the Mexican woman next to me at the internet cafe who is talking VERY LOUDLY on her cell phone. So loud I can hardly think, and then I tear off a peice of paper, wad it up and stick it in my ear on that side to try and block the conversation from which I understand 1 in 8 words, the rest sound like SLDKFJD CKLSDLKS SKDKFEOWK mi amore.
We are the only two here, so I don´t understand why she chose to sit right next to me where there are a dozen other computers. Must like my perfume or maybe I´m a people magnet again.

I look over to the attendant to give him the "please shut her up" look with my eyes, but he is busy chatting in messenger and managing his music downloads.

The Spanish teacher says that I should say:
"Senora, silencio, por favor" which translates to "Mrs. Lady, quiet please." but that would lead to other Spanish words which would lead to me having to say "Sorry, no speaky Spanish," ...again.

I would so the shush! sound but it would be mistaken for the hiss sound and that can only mean trouble for me, so for today I am just balling up a peice of paper and shoving it in my ear on that side.