Very bad service at theme park

I booked for a school excursion at the theme park for two separate dates being the 13th September together with today the 19th September . The first trip went well there were no issues ,however this time around we were denied access whereas the payments were made and got called in the morning to confirm our booking which that was done. When we arrived were made to wait for 3 hours without any assistance and the service providers/cashiers were rude and left us . We only got assistance after calling the manager who then made sure we got helped within 5 ‘minutes the service is appalling especially when it involves school kids who paid and never got any explanations or an effort to resolve it .