I would try setting in a complaint, but there is not much you can do. you cannot prove THAT was the cause of snails. And trust me, I have gotten the same from live plants, even from tanks that were not at all infected with a single snail. I found a way though, is either squish them and feed 'em to the fish (delicious....to them...), or siphon them up. Also, even if it is a "snail free" plant I'd rinse it with a bucket of aquarium water, shaking it gently to release any snails, then have it not in your tank (perhaps in another bucket of clean aquarium water) just in case there are eggs.
I feel your pain x.x My one 10 was covered in them...
Tip to get snails out: lettuce, or slice of zuchinni apparently works well. I had this one fake plant they adored and would cover o_O no idea why... it was a rather rough plant so it was taken out soon to protect my betta's fins :)