The moment i pasted this in my child theme’s function i was able to add tickets to my event (http://www.nieuwetijdskind.com/event/nieuwetijdskind-com-lezers-workshopdag-2015/) which i could not do before.
it is possible that my webdesigner did not update woocommerce the last time because of some bugs in Woo, but am not totally sure. Hope that helps
After adding some code you provided (Filtering to show WooCommerce Tickets prices) in my functions.php file the multiple tickets do show, so problem solved.
I sent a mail to support regarding my buying your plugin twice.