I don't think you've chosen the best place for suit shopping (or any kind of clothing shopping for that matter). I'd also suggest that you try the international designer labels, but I heard on here the other week that a lot of them are nearly empty because of import delays and restrictions.
I can't imagine you're going to find much at all going into spring/summer but you may find something at a shop like Chocolate (there's several branches...alto Palermo has one) which usually stocks pretty muted tones (though I have no idea what they'd have in the range of suits). Portsaid, Markova and Kill usually have formal womens clothing too. If you can get away with a skirt and shirt, you might have a bit more luck in the shoppings.