Please Help Needed!

Phone gurus in the house here is my plight.I use a nokia 6230i and anytime the battery is fully charged it doesn't last 4 more than 4 hours either i use it or not the battery runs down.I need suggestions as to whats up with the phone before i take it 4 repair.your  contributions would be hihgly appreciated.

the battery is not the fault cos av used up to like 4 new batteries and still get the same result.