Landscaper planted the wrong trees.

We had our landscaper install three cherry trees in the late fall - 1 white Yoshino and 2 Kwanzan. Now that they are in bloom, the Yoshino is pink (lovely, and no problem at all), but the other two are white Yoshino instead of Kwanzan. At $600 per tree installed, we are a bit disappointed. The landscaper is blaming it on the tree farm giving him the wrong trees. How would you address this? What are some reasonable options? We like to remain flexible, but we work with this landscaper frequently (with mostly great results), and we don’t want to ruin the business relationship while not being complete pushovers, either. Thanks in advance for any advice!