No answer to support queries; waste of money

I downloaded this plugin, but found that you had to pay in order to get the Twittercard with large image, which is what I really wanted.

I therefore purchased the Summary Card with Large Image, but I have been unable to get either that or the original plugin to work.

I have had no response to support queries I sent them weeks ago, or to my request for a refund. Eventually I found out that I could use Yoast to send twittercards with a large image free of charge.

This plugin has been a complete waste of time and money. I feel conned.