BEFORE YOU RETURN IT
If you have windows…
run command.com (just do a search for it it will be there)
In the old school command line box that no one seams to care about anymore type
chkdsk e: /F /X
where e: is the drive letter assigned to your usb stick.
Wait for a few minuites at most and you will probably have a perfectly writeable usb stick even if no errors were found.
Worth a try to saves days of waiting for a replacement in the mail or a trip into town.
