On 4th IPHONE 4S battery issue Need Help

I am on my fourth or fifth iphone 4S. After a few months of owning it only takes few hours for the battery to discharge completely.Tried everything apple recommended, the last time they gave me a new phone again told me to Restore to original settings and then sync individual items back, they thought it was a software malfunction somewhere, tried this and  worked for about 2 months I think the problem started again on this last phone after I installed the updated operating system, I tried the recommendation apple made which had worked when the phone was new but not this time. I am tiered of changing phones has anyone else encountered this?