Nixon Land Surveying

I had a survey completed back in February that required two sides of my property marked . I never received a plot or any additional information until 1 week ago. I received a statement wirh the following written on it. This is 92 days overdue pay immediately. Did not particularly care for the tone since was first statement but 5 days later I put payment in mail. Then 1 week later I receive a bill threatening court action. My thoughts are proceed with caution not sure if a billing problem or mail problem but I am really disappointed.