Hi Alex,
Thanks for getting in touch and so sorry to hear about the purchasing issues!
Just to clarify, we do not sell a plugin called “Users” but we do sell the following plugins:
https://theeventscalendar.com/products/
The email address you mentions refers to this site: http://iplusstd.com/
I see one of the products listed on that site is called Event Booking Pro. Is that what you are looking for? If so, you might want to reach out to that email address because I do not believe our plugins are what you are looking for.
We do have one plugin called Events Calendar Pro and another one called Event Tickets Plus, so I can see how easy it would be to mistake our products for that other one.
Cheers!
Geoff