I'm sorry you're having such trouble. This is the problem...you've had a reflux issue that created the need for a Nissen fundoplication. When you undo this barrier that was created to stop that reflux, it will start up again in full-force.
Is there any chance you can locate a top-notch, experienced, most outstanding Nissen surgeon who can do the job of creating a wrap properly and fix this problem?
I truly hope you find someone who can help you. That person is out there...you just have to find him/her.
Thinking of you, and wishing you the very best,
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”