Taiyo Yuden is a manufacturer, not a brand name. When you buy Memorex, (or as I call them, Memowrecks) the discs won’t have a “Memorex” MID, they’ll be CMC MAG, or, if you’re lucky, Prodisc. Even in Japan, TY retails their media as “That’s.”
Taiyo Yuden only sells media directly in bulk, i.e. packs of 100 or more, and this media will be unbranded.
If you sought out Taiyo Yuden media and bought some on the clear understanding that said media was Taiyo Yuden, they had no cause to send you that 4th rate crap instead. TY would certainly never have authorised them to do so, of that I am certain.
Obtain a refund by any means necessary. Then do a Google Products search for 8x Taiyo Yuden.