I need some help with a refund issue in Lithuania.

Yesterday I was supposed to take an intercity trip. It wasn’t an official bus company it was a small minibus/van service. I had a discounted student ticket (ISIC), but they refused to accept it and forced me to buy a full-price ticket.

The staff told me to send an email for a refund, so I did. However, the reply I received says that they don’t refund tickets after departure based on the transport rules.

The problem is: since this wasn’t an official bus company with a clear brand (just a small minibus), I don’t know who I’m supposed to contact for a refund. Where am I supposed to send an email for these unbranded transportation services in Lithuania?

Does anyone know which authority handles this.