Nokia 5318 xpress music
Attery not lasting even for 24 hours

I bought a Nokia 5310 Xpress music on 7/7/08 from moblie store in Trivandrum. I initially charged the phone for about 4 hours when the phone indicated full charge. I dint use any music service or much calls still the next day after anbout 16 hours of last charge the phone went dead.again i charged for about 3 hours and this time it lasted for 17 hours only. I have hardly used it for 5 days and I am terribly disatisfied with its performance! Is it something wrong with the battery or its software. now I have put some music into it but i am afarid to listen to it for fear of losing its charge. my colleague who also bought the same kind of piece experiences the same problem. Please advice