defective replacements

I bought the ped egg and it didn'e wrk well at all.  Other people said it did, so bough 3t replacement blades at Bed, Bath & Beyond and tried one and it worked great.  After that got dull, tried one of the others in the package and it wasn't even raised and did't work at all, OF COURSE YOU DON'T FIND THAT OUT TILL YOU'VE HAD THEM FOR AWHILE AND THROWN THE RECEIPT AWAY.  It's so annoying to buy something and think they will all be the same and have them be defective.