I have sewer line that is over 100 feet to the cities sewerline, and need to add a y cleanout port in the middle of the line. Being a senior I need to know the estimated cost. The last plumber dug the hole, punched a hole in the line, cleaned the line only halfway. Had to come back the next week, and charged another $200 and still the line does not drain properly.

We can not give estimates. Too many factors enter into bit, However, We may be able to help with the problem if you can furnish us with information.
Why would need another clean out? Is the line backing up? What material are the pipes? How old? What did the plumber tell you? Give us all the information you have. Back to you, Tom