Hostel payment

Hello everyone, my friends and I booked a hostel for a couple of days in Prague. While the terms and regulations explicitly say that payment can be made in cash or card, they are telling me that due to the “type of reservation” I have made (they won’t tell me what “type” it is) EDIT: (forgot a crucial part, my bad) they say I MUST pay with cash. Is this a common practice? Any idea why they would do this? Where I’m from (Italy) businesses are required by law to let you pay by card. It sounds fishy, that’s all.