WHITE IPHONE 4S 64GB LIKE BRAND NEW !

OK HERES THE DEAL I HAVE MY IPHONE 4S WHICH SEEMS TO HAVE A PROBLEM ALTHOUGH ITS INTERMITENT IT RANDOMLY GOES IN AND OUT OF SERVICE ALTHOUGH MY AREA HAS A GOOD CONNECTION. I HAVE BEEN READING FORUMS AND HAVE CALLED APPLE A DOZEN OF TIMES FOR A SOLUTION AND STILL NOTHING HAS WORKED. THERE ARE VIDEOS ON YOUTUBE SHOWING HOW TO FIX VIA ITUNES BUT I JUST DONT GET IT SADLY I AM SELLING FOR £400 OVNO AS IT IS A 64GB MODEL AND IS IN PRISTINE CONDITION I HAVE ONLY USED IT LIGHTLY FOR 2MONTHS AND HAS BOX AND ALL ACCESORIES I WILL ALSO SWAP FOR LATEST BLACKBERRY OR IPHONE 4 WITH CASH ON TOP IM AFRAID THIS IS COLLECTION ONLY AND I WILL NOT POST UNDER NO CIRCUMSTANCES COLLECTION IS FROM FELTHAM THANKS NICOLE