Admission tickets are often resold via ticket resale websites. This practice is allowed, but it is prohibited to make a profit on such resale.

Did you buy a ticket through a resale site at a higher price than the original ticket price? Then contact the resale site. The reseller is obliged to refund you the difference between the price you paid and the original ticket price.

Did you make that purchase with a credit card or through an online payment system (e.g., PayPal)? Then dispute the payment and request a refund.

Websites that resell tickets are usually foreign websites, where regulations on ticket resale are not always strict or regulated.