This discrepancy may be due to this store's warranty policy vs. what Apple provides. First thing to check is this store an Authorized Apple Reseller. If so, the Apple Earbuds should come with a one-year hardware warranty against manufacturing defects. Your country may have other warranty regulations in addition to those.
Regardless, no one here can help you as we are not Apple employees. If the store doesn't assist you with this, then you can certainly contact Apple Support for further assistance. You can do so simply by selecting the "Support" link on the bottom left-hand side of this forum's web page.