Refunds are available through sales@stardock.com . . . but first let's try to see what's wrong.
The first thing is that Keepsafe only backs up files that have changed. Mp3s rarely change, right? Could that be why some are not being backed up?
Also . . in XP you can find the manual here: C:\Program Files\Stardock\ThinkDesk\KeepSafe\KeepSafeManual.pdf