(@fbc21ca Thanks for sharing this with us. I’d suspected, given the dev’s lack of activity they may have abandoned this plugin, even for their paid customers, but your confirmation is very helpful.
If getting a hold of them to get a refund gives you no more success then getting tech support, I’d recommend you work with your payment processor, be it your credit card provider, or PayPal or whatever you used, to get a chargeback on your purchase. The fact that they have completely and utterly failed to deliver your purchase, as long as you can produce the receipts, or they fail to counter your claim, should be sufficient to get your money back.