Beginning in the middle of the first night (night of December 25th) and at least 2 times per night thereafter, the heating unit for the apartment made a very loud banging noise - so loud that it was impossible to sleep through. (It appeared to happen when the unit was cycling off.) This was not just a "clicking" noise (that happened too), but a very loud banging. We notified Anna's daughter, who is listed as the local contact. She was out of town, and Anna was out of the country. We were told that we needed to be at the apartment in order to have a repair person come, but we had plans and could not be there. We sent a video, as it seemed as if they did not believe us that this was not a normal clicking sound for the heater. As a result, the unit could not be looked at until the next day. Someone came, but they apparently could not replicate the sound, which meant that the same thing happened every night. We were accused of being "rude" for complaining.