Since everyone here seems to be so wonderful at giving advice and how to frame complaint letters well, I submit the following for your approval and/or suggestions.
Any suggestions are welcome but I would like to send this by the end of the day as the temperature is supposed to drop to near -35 C by the end of the week.
As you are aware, there have been problems over the past few months regarding the heating system at (building address). It was fixed for a time but last week started acting up again. Currently the situation with the heating system is such that when it is turned on it makes a very loud rattling noise complete with vibration that makes sleep or everyday activities in the apartment impossible. Therefore the system has been turned off in the evenings, leading to the apartments being too cold.
My husband and I would like some reassurance that the heating system will be working properly soon as the temperature is supposed to drop drastically later this week. Last time our apartment temperature dropped to 13 C, which is unacceptably cold.
We trust that this will be corrected in a timely manner.
Please let me know the status of the heating system repair by return email if possible so that my husband and I can have some peace of mind.