faulty products

i bought a toolbox 85 piece at checker exactlly 3 months ago and about a week ago the hing came loose so i when too exchange it today ,when i was there one gentleman says they dont have stock then another says they must have...so when waiting for them to tell me if they have stock the gentleman nhlanhla nkosi tells me he will not exchange it as its not within 7 days, so if your product lasts 7 days and falls apart after its acceptable ,that is the worst service for customer i have experiences as its the weld on the hing which is a faulty product not the tools itself ,how do u tell a customer you will not exchange a fault device