i work for a mobile phone company on the handset faults department. if youhave insurance with 3 they will replace your handset if it was sent directly from them, if it was through phones 4 u and is within the first 28 days they will also replace this, if either of those options fail then you can send it back to nokia under the guarentee which i think is 24 months (but they do not give you a replacement in the time it is away), i would also suggest you perform a master reset which can usally be found in the security settings on your phone( it may ask for a security code which will be12345 unless you have changed this), if you are going to do this then back up all of your personal data such as pics, vids, and music
hope this helps.