Here, I present to you my save file, ready to start the Side Quest: Sub-Level 13, to earn the achievement "Who You Gonna Call?"
with Nisha character, level 42.
Be sure to select this character.
You will find yourself on the "Outlands Canyon" map, where you'll find the mission.


Here's the save file.
Download it HERE [drive.google.com]
Most likely, Extract it and copy the files directly in the following directory:
After doing this step your directory should look something like this:

Note: I'm not certain which file it is, so I've uploaded all the files.

To earn this achievement, you should play this mission with three other players.
If you are playing alone, THIS GUIDE will help you solve the problem.
It worked with me.

• This mission consists of 2 parts "Sub-Level 13" and "Sub-Level 13: Part 2"
  you should complete both of them in order to gain the achievement.
  
• At the end of the mission, you will have two options to choose from.
  You are free to select any of them, but I recommend choosing "Use inverter" option to finish quicker.
  
• Then, go and turn in the mission.
  
• You will receive the achievement. Congratulations!

Good luck, and thanks in advance for any support!