"The world's most trusted and quoted source for games market insights and analytics"
Key part - analysts and market insights. So, they don't have concrete data like NPD for US market, GFK, EMEA for Europe, Media Create / Famitsu for Japan.
Why you always link some UK retailers, Amazon UK in that case? Market exists outside UK. Fnac is biggest retailer for electronics in France. And France is big market too. I've didn't have found "some" retailers. Retailers which i've provided are one of the biggest in their own country or across Europe.
So, Brazil and Mexico are one of the few countries where Xbox is selling better than PS. Americanas is one of the biggest in Brazil and XSS is available there :
In Mexico is available too
To me, XSS isn't hot stuff nor it selling well when it's a new console.
Who cares about your opinion of what is considered selling well or not?