It's happened before and it'll happen again. Apple's lanyard headphones for first and second generation Nano iPods have some kind of inherent weakness that means that one earpiece silences after six or so months before the other ear gives in a month or so later. So I've been around the loop a time or two to get Apple to repair them
The lanyard headphones - they hang the iPod around your neck with the ear buds built into the next strap - unusually don't have an individual serial number. So the warranty repair is handled against your iPod. Problem is that once your iPod is out of warranty, you have to prove when you bought the lanyard headphones, and email through your proof of purchase.
It would have been nice if they'd given me the correct email address on the first two phone calls. And nice if after the third call they hadn't returned a terse email to say that the warranty date of the iPod couldn't be updated .. when I only needed them to record the purchase date of the headphones.
Fourth call, someone was going to talk to their boss and call me back.
Fifth call, and they could see I'd emailed in the proof of purchase - rejected a second time with a different terse email - and agreed to ignore that and send out the replacement.
You have to send in the old bust ones otherwise they charge you for the replacements.
The size of the prepaid return envelope? Larger than an A3 piece of paper! You could fit a Macbook in there ...
Update - Tuesday - The problem of Apple sticking the sender's address on the front of the envelope is that the Royal Mail delivered the bust headphones back to me today, instead of using the Apple's "to" address ...