I booked a seat on the Warsaw-Torun train for tomorrow. The FAQ on the PKP Intercity website says that if you're carrying baggage that won't fit overhead or under the seat, that you need to pay an excess luggage fee. Since I've got a larger backpack, and the fee was only 5.10 PLN, I paid the fee.
So now my ticket clearly says that I have paid for "stuff" (literally rzeczy), and I'm curious how this works. From what I've read, luggage storage is limited to overhead and under-seat storage. You pay this fee when you think that this storage option isn't sufficient, but what does it actually give you?