I think most people with iphone 5/5c/5s are going through the problem of '''unstable wifi, no bluetooth, messed up clocks and the gps.''' No one has given/can find a legitimate answer. For the time being, change the clock manually and '''never lock your screen''' (auto lock on never) because the clock freezes when its on the lock screen and works on the home screen. And for the wifi, i guess you'd have to be quite patient because my iphone 5c connects than a minute later disconnects so you constantly need to connect to the wifi.
UGH SOME APPLE GOD PLEASE COME DOWN AND HELP US THROUGH THIS NIGHTMARE WITHOUT SPENDING MONEY ON A NEW PHONE!!! :(:(:(:(
hope this kinda helps