200gb microSD card failed straight out of the box, unlucky or are they unreliable?

I’ve bought a Sandisk 200GB microsd card and it’s failed straight out of the box, it started misbehaving so I tried another card reader and it was doing exactly the same (first was a Sandisk imagemage card reader, second an onboard one).  It came from Amazon UK and all appears genuine, h2test2 has marked it as defective:

Error reading file 'D:\1.h2w', offset 0x14700000. (The request could not be performed because of an I/O device error. Code 1117) Warning: Only 187713 of 187714 MByte tested. The media is likely to be defective. 154.7 MByte OK (316880 sectors) 172.2 MByte DATA LOST (352816 sectors) Details:162 MByte overwritten (331776 sectors) 0 KByte slightly changed (\< 8 bit/sector, 0 sectors) 10.2 MByte corrupted (21040 sectors) 162 MByte aliased memory (331776 sectors) First error at offset: 0x000000000023e000 Expected: 0x000000000023e000 Found: 0x2cf560e87bc0749d H2testw version 1.3 Writing speed: 26.9 MByte/s Reading speed: 3.84 MByte/s H2testw v1.4

This is the fourth high capacity micro SD card I’ve had fail on me in the last couple of years (one Sandisk 128GB, two Samsung 128GB’s), I’m just wondering if I’ve been extremely unlucky or these cards are less reliable?  The finger points to the equipment I’m using but I use many other memory cards in the same reader and same device (the phone is a Galaxy Note 4) without issue.  Usually the failure is the same, they last a few weeks or months and then just out of the blue I can’t write any date nor format the card.

I’m just wondering whether to get a refund or try another replacement as I know Amazon UK don’t like a lot of returns, the phone currently has a Samsung 128GB card which has been working fine for the last couple of months.

that may be a fake card. contact sandiskl support and have them verify the authenticity. if it is authentic they can replace it. 

Just to update this, I finally got around to sending the card to Sandisk who verified it was a genuine card and have sent me a replacement which is now in my phone and so far seems to be working fine.