The USA Nursery theusnursery, usnursery charged for the order. not delivered, do not respond New Haven Connecticut

On the 6-th of May 2017 I have ordered online a young cherry tree. UsNursery was so generous that they even offered a free gift - it was a rhododendron. As usually, I have immediately received my order confirmation over email. After a week, having no shipping notice, I tried to call their customer service (203-267-0204). The call ended with "Mailbox is full" message. I tried this customer service number several times with the same result. Then tried to reach them over email (info@theusanursery.com) - no response. Repeated a week later- same negative result. Sent email cancelling the order and demanding my money back - silence. I am not a lawyer, so I do not know how exactly to qualify such mode of operation. Simply speaking - it stinks!