Hello @keodepchai
Thanks for your request.
You have described to us the parking situation on site and your personal impressions - all parking spaces at the station were already occupied. If you purchase a parking ticket in advance, you have no right to a free parking space. For the future, I ask you to park first and then buy the tickets.
If you have any questions, please call +41848 44 66 88 (CHF0.08/min).
Greetings, DafineM