Dr dre beats tour need help?

im 16 years old and i bought dr dre tour headphones like 3 months ago and 3 days ago the left earphone broke the headphone piece has come apart with the wires so there is no connection with the music and i was wondering if i could take these into hmv and exchange them with a other pair or get my money back as i have a warranty on them and i didn't brake them on purpose i took them out of the black case that come with it and the left headphone just come apart :( i have a one year warranty to and they cost me �100