Do you remember their names? They look like young Limelights or maybe Bobos, but if they are supposed to be pink they might be Zinfin Doll, Strawberry Sunday, or something similar.
If they are young plants they might just need time. Often the pale pinks ones will flower out pink, then age out white. And vice versa. Soil could be causing them to be all white.
That only works on certain types of hydrangeas and it takes a while because the soil must change first in order for the plant to uptake the nutrients, or lack of. Such as the effect of acidity on aluminum in the soil.
New cultivars have/and are coming out that will start blue, turn purple, and finish off with a pinkish tone.
More acidic soils tend towards the blues and purples and alkaline soils tend towards reds and pinks, but that's mainly in the macrophylla (big leaf) types.
Paniculatas will remain true to color despite acidity levels in the soils.
.....sorry, my nerd is showing
maybe I should ask first though 
