Hotel La Calcina in Venice

I booked this hotel for my mom for 9th June, 2025 via *******. I even got a message in ******* by the reception staff telling how to reach the destination. When my mom went to the hotel for check in, the night staff there said they don't have the reservation. My mom called me (overseas) and my brother and we tried to talk with the staff. His name is Anthony, and he clearly said that there is no reservation. I sent the email and message of confirmation to hotel's email. He then said that it is a fake *******. I was shocked, as I have used the same link to book hotels in Santorini and Rome and they both were confirmed. The staff then insisted us to pay for the night. I asked him to call the manager may be and ask him about this as there might be a confusion. He said his manager does not work until next day evening. He said to pay now and then talk to the manager tomorrow. I told him that we just booked for the night and my mom is leaving to Rome tomorrow. He just kept on saying that we have to pay. Later, I don't know what happen, he said he will check another computer and was talking to his manager. He then at last came to my mom and said that he finally found the booking. This was terrible. I was on the phone with this staff for hours and he at last did not even apologise. I don't know whose fault was this, hotel or ******* but I think there is a way to handle this situation and I can clearly say that he was not handling it well professionally.