OP, sorry for hijacking your thread, but I'm in sorta same predicament as you.
I used to buy western classical earlier at Landmark, Forum (Koramangala). They had excellent collection in this genre (labels like Deutsche Grammophon, Decca, Telarc) as well as many 'non mainstream' genres (soundtracks from Ennio Morricone, Operas, Jazz, Gospel, etc.).
But after their takeover by Westside, their music collection has been tragically gutted. All I see now are mostly 'latest best sellers' like Justin Bieber, Lady Gaga etc. Sadly, they're no different now from their competitors like Reliance Digital or Planet M (if they're still around, that is).
Coming to the point, are there any places in Bangalore (preferably around Koramangala/JP Nagar/Bannerghatta) that feature a decent western classical collection?