If you know in particular the kind of dog she wanted, a cross bred dog is never a good route to go because there is no way of knowing what the end result will be. (without even getting in to the other reasons 'why' it's not a good route
) There is no way this person could say what the dog will look like at all.
That's just a lie--no other way of putting it.
I hate to say, but sounds like your neice was taken advantage of. I'm sure that the "breeder" (and I use that term loosely) told her exactly what she wanted to hear so that she could close the sale.