Michelle,

Make sure you charge the unit using a working AC outlet. It sounds funny but sometimes our customers plug their speakers to switched or non working outlets.
Also be sure to charge the unit and use it after you charge it, don't let it charge and come back days later assuming it's been recharging constantly during that period of time.
Let it charge for a couple hours before the time you plan to use it. If it's still not giving you more than a few hours of playback it could mean the battery has aged and reached the limit of recharges in its useful life. If you need a replacement battery you can give us a call or contact your local dealer.
Take into account also that the unit can give you many hours of playback if you set it to an average listening level, but if you're playing your music very loudly the playback can be reduced dramatically.