What you are writing is not true.
1. "bought Your quizx plugin without updates"
I did send you an update on 2016-07-01
2. "sent You message many times without answer"
I received a message on 2016-07-01 and answered the same day, next answer on 2016-07-18, your reply on 2016-07-18, my reply on 2016-07-25. Afterwards there were no other emails from you. Just a one-liner-PN from 2017-04-20, which I missed.
3. "I need ability to post standard questions and quiz posts om same page"
This is not possible as said clearly beforehand.
4. "ability to post many questions in ONE quiz post"
Not possible by design.
5. "updated version of this plugin"
I updated the version two months ago, internal update running for math sites. I can send you a copy if you like. However, it is math specific and I am not sure if it will work out of the box.