Radisson Blu Hotel, Hamburg in Hamburg

Had an awful experience and will make this review for improvement purposes. I booked one night with breakfast and while I was sleeping, someone entered my room at 3:45 am. I was startled and shouted "hey!" and the person said "oh, there is someone here" and left, but without identifying themselves or saying sorry. I didn't manage to see the person, but I was quite scared. I called reception and they said it was probably housekeeping, as the room seemed empty in the system. But this makes little sense as when I arrived to the room it was already clean (and additionally, what hotel does housekeeping at 3:45 in the morning?!).
In the morning I went for breakfast and when I gave my room number to enter the breakfast site, they told me that it didn't appear in the system. They let me in anyways and said that they will sort the problem out. After breakfast, I went back to my room and my card didn't open the door! Went to reception to complain and they gave me a new card which worked. Later, I went to do check out and again I didn't appear in the system. They had so many opportunities to fix this (at night, during breakfast) but didn't. I was running late for meetings but still had to wait for them to sort this out. All in all it was a horrible experience, after they entered my room during the night I couldn't get any more sleep, as there was no way to lock the door from inside.
After all the troubles, as a compensation they gave me a courtesy drink in the bar (which I obviously wouldn't even be able to use as I was leaving the city that day). Really bad experience and quite unexpected for Radisson Blu... very disappointing.