Did the replacement come with any warranty statements? A battery probably wouldn't have a very long warranty on it, so I doubt you'll get much help from Apple. I think the only condition they would replace a battery on a computer as old as that, would be if there were a government-mandated safety recall.
No chance Apple's going to cover a 1-year old "free" battery, and can you even imagine that the original it replaced would still be operational, anyway? You can easily find a great OEM-quality 12" G4 battery on eBay for $50 shipped.
Shouldn't emailing the mythical sjobs be a last resort? Not want to sound lame but maybe this didn't warrant an email there.