GOODBYE CNA, YOU JUST LOST ANOTHER CUSTOMER

Bought a new SD card from the store in December just before going on holidays [needed more storage, old SD card was not serving the purpose]. I need storage as I do most of my work on my phone, bought a brand new SD card, inserted on my phone and it worked for a number of hours then BOOM! the SD card returns an error message when I try and access information, SD card must be formatted, all my work on the SD card gone. Tried formatting the card and no luck, took it to my IT guy and he tried formatting the card and dololo / nothing. Went and bought another SD card so I can continue working, no problems on this one. Now fast forward to Jan and I try and return the SD card to the one CNA that I use on a regular basis and I am told that the card is broken and they cannot exchange it [it can read and provide error messages however it cannot be exchanged as it is broken], a product that never really served its purpose, unfortunately I did not inspect the product when I purchased the item, immediately put it on my phone after purchase and it worked perfectly be it for a few hours. Could this be a product failure defect? Why is it providing error messages if it is so broken? Could it be that the same item bought from your competition works far better than what you offer? The latter being true then I will continue buying from your competition in order for me to save myself a few rands. Having worked for you in the past makes it so much more disappointing, goodbye CNA, hope my little contribution helps your EDCON recovery.