Here are some tips that may help you: http://discussions.nokia.com/t5/Pool-of-Knowledge/
your local Nokia Care point: http://nokia.com/support
Let us know how you get on.
Battery capacity may will decrease over time, on average this will be about 20% per year but may be more depending on usage patterns. If you find the time between charges decreases dramatically please consider replacing the battery. You can buy a new original battery through a Nokia Care point or your local Nokia retailer.
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