What is the format of the dunning letter sent by the property management company to the construction unit?

This can be a work contact form or an ordinary letter. Write the name of a construction enterprise, and then say what happened to a project constructed by your company somewhere. I have repeatedly verbally informed you of maintenance, but I have been unsuccessful. Now I will inform you to repair it again. Then you are famous. It is better to send another copy to the developer. Remember to let the other party sign for it. There is no fixed format for this thing. The most important thing is to pay attention to evidence collection.