PHONE NOT FUNCTIONING ON 8TH DAY

ON THE 2/02/2016 I HAD TELEPHONICALLY UPGRADED MY CURRENT CELL C CONTRACT.I COMMUNICATED WITH SIPHO.I UPGRADED TO A LG G4.I RECEIVED THE PHONE ON THE 3/02/2016.SO IT WAS THE SAME NEXT DAY I HAD RECEIVED IT. THIS DEVICE WAS USED MOSTLY AT WORK DUE TO HAVING WIFI.THE PHONE WAS ALSO SLOW ON WIFI SO I THOUGHT MAYBE IT WAS JUST THE WIFI BUT BROUGHT MY SUMSUNG TABLET WHICH WAS MUCH QUICKER WITH DOWNLOADING.ON THE 8TH DAY AFTER PURCHASE THE PHONE DID NOT CHARGE TO FULL 100 PERCENT . THE PHONE BATTERY DIED WITHIN SECONDS.WHEN YOU PUT THE PHONE TO CHARGE THE PHONE WILL GO TO FULL 100 PERCENT IN ABOUT FIVE MINUITES.I CALLED THURSDAY(11/02/2016)TO REPORT THE FAULT TO CELL C.THE PHONE WAS PICKED UP ON THE 12/02/2015.I WAS TOLD IT TAKES 7 DAYS TO GET THE PHONE BACK.PHONE WAS SENT FOR REPAIRS TO LG AND SURPRISINGLY THERE IS NOTHING WRONG WITH THE PHONE.IS THIS NORMAL FOR A BATTERY TO DIE IN A FEW SECONDS AND THEN GET BOOSTED TO 100 PERCENT IN JUST FIVE MINUITES.LG SENT MY PHONE BACK TO CELL C ON THE 18/02/2016.I WAS TOLD MY PHONE WAS DISPATCHED ON FRIDAY AND TODAY 22/02/2016 I CALLED AND WAS TOLD THAT THE PHONE IS STILL AT CELL C.WHAT TERRIBLE IS THIS?WOULD NOT RECOMMEND CELL C TO ANYONE