Write to Diamond desk - forget about get ANYTHING from the hotel, it's Europe, you paid for a room to sleep and you got it. Did you incur any financial loss? IF not, there's no court case also forget about the front desk because even the one in the US has no real power to comp anything. Even the GM may throw you like 3k HH points as an "apology".
I do agree that one should assume that everything functions - the hotel is supposed to make sure everything is right, I normally check if there's any major issue with the hardware and the minibar has everything listed