When complaining mention that you do not believe the phone was fit for purpose. im not sure were you live but in the UK this is something that the the person dealing with the matter cannot ignore. if you feel that you were not a fault i am sure this should work. especially as GeneralAntilles says that have already claimed they are aware of the issue

do some research there are loads of info on the web

http://whatconsumer.co.uk/it-is-not-fit-for-purpose/