IPhone 5 carphone warehouse?

I have an iPhone and the lock button isn't working properly so if i take it back to carephone warehouse will they change it and if so do i need to take anything with me

I guess it depends if you took out insurance on the phone, failing that if you're the only owner of the phone from new, in your box should be a 24month Apple Warranty you could try ring up and ask Apple them selves about it