Slabtek Problem

We own a 3 year old home in Lewisville, Texas. Our foundation is a slabtek foundation, which means it was poured post tension slab then raised kind of like a pier and beam but all concrete.
My problem is the back bedroom bathroom toilet keeps rising, we have had the pipes cut and re-flanged 4 times @$395 a pop and the same concern keeps coming back. It gets repaired every time but within 2 months its about an inch off the ground which makes the toilet useless as you can not sit on it.
I have used the company that installed all the plumbing to fix it 2 times and each time they tell me this should be the last time, I am starting to wonder if the toilet is not a symptom of something wrong under the home. We had a pipe on the other side of the home in back burst and dump our washing machine water under the slab. That pipe was sheered off at the elbow. Instead of digging out the entire side yard to tunnel to the pipes I wanted to see if anyone has run across this, or has had the problem personally.

If I am understanding you correctly, it sounds as though the slab is sinking on it's piers. I wouldn't be calling a plumber, I would be calling the builder and a structural engineer.

I agree with Phish. Your pipe is not moving.

It can be deceiving. Like when you are at a stop light and the large trailer next to you starts to move slightly. For an instant you are slamming your foot on the brake thinking you are rolling into the intersection.