ibook recharge problems

I have an ibook that is about 3 years old....about last month it quit charging and it wont even hold a charge when plugged in...there is also no light on the powercord when plugged in. I have taken it to the computer people at my school and they tried a new power cord and then they tried to re-solder the plug jack for the computer, and when neither worked they gave up...anyone have any suggestions, or know how much it would take to get it fixed?