iphone 4s will not charge

Previously, I have installed iOS 9 which caused lots of overheating and malfunctioning which then stopped. In the last week I have had problems charging the phone and not receiving calls or messages. The new software had been downloaded but not installed even though I repeatedly set it to install overnight it never did. Today the phone would not charge at all until I attached to my iMac which intermittently acknowledged the phone was connected and seemed to kick start the phone to charge. It has fully charged but looses charge rapidly and very difficult to get it to re-charge. Have been unable to book a genius bar appointment as none available and the internet diagnostic test failed repeatedly. As my son's iPhone 5 has died completely with this update, i do not think I am alone but no information or help from Apple.

iPhone 4S, iOS 9