We were kept up all night by an extremely loud sound from the air con (both when on and off) that came every 1,5minutes. The reception manager came up and apologised, but said there was nothing to be done, however promised to discuss a compensation with his manager. We recorded the sound, and it lasted throughout the night. Next morning, the new person in reception said that it was not possible to compensate us as we had already paid... I let her know that this was ridiculous, and she then promised the manager would get in touch with me later that day. He never did.