Man, if that's how you come out of the gate with an issue with a product someone sold you, I don't blame them for their response. More bees with honey than vinegar, ya know? That said, if I dropped that kinda coin on seeds and the results were that bad, I would definitely be upset. It appears that he didn't slam the door in your face and left it cracked to come back in and have a chat. I personally, would reach back out with my apology ready to go, calmly explain the situation and that I was heated on the first attempt at contact. I would apologize again and see if there is any sort of mutual resolution that we can come to.
I understand why you are mad, but if you want it resolved, stop and breathe a little and then approach it with a little tact. Best of luck to ya, man. I hope y'all can resolve the issue.