wifi greyed out after iOS 7 update

Hello,

I updated my iphone 4s on the date the new IOS7 was available. Until that date my phone had been working the best. After installing this update the wifif button became greyed out. Apple wont replace or repair the phone becuase its 100 days out of warranty and my service provider O2 say it will cost me £342 to repair. Why should I have to pay I didnt break my phone. any ideas someone mentioned EU legilsation but both apple and O2 have ignored this.