Unfortunately it does happen from time to time, there can be many reasons why, sometimes it is personal issues and are away from email/social media, sometimes there is a backlog in orders, sometimes supplier issues, I'm not trying to make excuses for whoever it is but I suggest trying to contact them once again. If they are on Facebook try there, as well as email and private message, a lot of suppliers are on forums.
I have had an issue myself in the past, I just kept sending messages via email and posted on their Facebook until I finally got a reply. It is hard but try to keep if civil, it doesn't help to escalate things even with the frustration you have.
Did you pay with paypal, if so could you start a dispute?.
Good luck and I hope it is something that will work out for you soon.