I recently stayed at a hotel in Munich for six days. For three of these days, I couldn't connect to the Internet (they had this problem with their system where you'd get disconnected about 30 seconds after you connected). The room also had a foul smell which, as it got stronger, I traced to the bathroom drain; I was moved out of my room into another room, which was smaller, plus I had to move myself. I'll also mention that I had asked them for cables to connect my laptop to the monitor and the room, and they didn't have those.
It's not a fancy hotel, but not a cheap hostel either. The nightly price was 91 EUR, including a very nice breakfast.
When I checked out, I complained about the first two problems - although perhaps not very assertively. What I was offered was a discount equivalent to the price of a soft drink I had taken from the mini-bar. Since I was in a hurry to catch a train, I did not argue - but I do feel I got short-changed and I should have demanded more; say, one of the days off.
My question is: Is there a customary rate or level of compensation in such cases? And if so, is it at the level of a mini-bar drink, a meal at the hotel restaurant, a free night's stay, or more?
I'll mention that the lack of Internet access was an issue for me, since I was attending a conference and need to access resources on-line before and after each day.