Garner Hotel Dusseldorf - Main Station by IHG in Dusseldorf

Yesterday evening we arrived at the hotel and went to the reception to check in. Unfortunately, we were told that someone had already checked in using our names. We explained many times that we had just arrived and that this could not have been us, but the receptionist did not believe us and kept insisting that someone was already checked in under our reservation.
The receptionist was very rude and did not speak to us politely. We were shown a reservation paper with a signature, but that signature was not ours. Instead of solving the issue herself, she told us to go to the room and call the people who were staying there to ask who they were. This was not our responsibility, and the problem was clearly caused by the hotel.
Because we were very tired, we finally agreed. We went to room 427 and asked the family there to come to the reception. It turned out that they had the same last name as us, but all other details such as date of birth were completely different. Despite this, the reception had allowed them to check in and sign under our reservation. This shows a serious mistake, as proper identification (passport or ID) should always be carefully checked during check-in.
In the end, we were given a different room. The room was okay, but nothing special. Overall, I would rate the hotel 4 out of 10. Breakfast was also okay, but not great