HELP. 3 inch inside flange broken in pipe

I have a totally broken all the way around toilet flange. It broke off inside the pipe which is only a 3 inch pvc. So the flange is not usable at all. Of course, its on the basement floor which is of course not level, which is why it broke. My question, do i risk cutting out the old flange which is about 3 inches below the floor surface on the inside of the 3 inch pvc pipe and glued in there very nicely. I worry that I will break the 3 inch pvc pipe that is running under ground in the cement floor. Or should I just scrap it all, dig it all up, and install the correct size discharge pipe. I could also take the asy way out and install a 3 inch "repair" flange inside the existing broken flange, but that will really cut down the diameter of the pipe for the waste. It was already backing up before quite a bit. Thanks.

flange

It broke because it was plastic, not because the floor was uneven. Whatever you do, you do not want to leave that portion of the flange inside the pipe. If you glue a new flange on the outside of the pipe, then it will stabilize the pipe so you can cut and peel the piece out.

cutting not working

any advice onhow to cut out the glued in flange, I am trying to cut it, but it is fused to the outside pipe.

not sure if it broke just because it was plastic but maybe flange was set to high putting stress on the flange not the floor.

Anyway isn't a pvc flange glued to the outside of waste line as a coupler would be? and a 3" waste line for the toilet should be adequate.
I also agree not to reduce the 3" waste line any. Breakout the concrete and dig it up first.

You will need to cut several grooves in the flange from top to bottom. Then a 1/4" wood chisel or a screwdriver can be driven between the resulting strips and the pipe and peel the strips off. You likely won't get the pipe perfectly cleaned off but that won't matter. I know they make flanges like the one you have that fit on the inside of a 3" pipe, but they are not a good choices. They cut the inside diameter of the drain too much. Get a 3" flange for the outside of the pipe. That likely will mean you need to chisel out some concrete to make room for the new flange.

flange

Before I try to remove a piece from the inside of a fitting, I wrap a hose clamp around it so it does not crack. In this case it cannot be done, but putting the new flange on it would do the same thing. Then, once couple of closely spaced cuts are made in the internal flange, and the narrow piece removed. then a narrow chisel or screwdriver can be inserted between the flange and the pipe and separate the two, working around the circumference a bit at a time. Often it works better with two screwdrivers. One to hold open the gap you have startedand create pressure, while the second one is used to create additional separation.