Ever hear of REI and lifetime warantee?  When a company says there's a lifetime guarantee, you definitely should request replacement.  That is your only recourse for them making sure they deliver a good product.  People like you "without nerve" allow companies to get away with producing/selling an inferior product adding insult to injury when they don't even have to honor the very marketing tool that may have tipped the scales for a consumer over another company not offering a guarantee.  Don't be a doormat.