J. A. Darke 
Tech Fury [PDF ebook] 

When Emily Lemon wakes up to a song she’s never heard before blasting from her mobile phone, she has a weird feeling. But it isn’t until she gets to school that she becomes suspicious. Why are the teachers acting strangely? And why are the computer screens showing personal information about her and her friends? When they display the message ‘DOWN WITH HUMANITY’, Emily fears this isn’t a joke and goes in search of her dad to escape a technological takeover.