Jetting is meant to clean walls of pipe that has decreased in effective size over the years as result of stuff sticking to walls. Jetting is also far more expensive than snaking.
Were I buying the house or in your position I would have another company make a camera inspection and give me the tape plus a written report. It is neither required nor wise telling them details regarding bellies. Did present plumber run a camera through lines?
While deciding,absolutly nothing in toilets other than body waste and toilet paper. That means no Kleenx,no paper towel,no sanitary napkins,no baby wipes,no wet wipes. Pull back as much as possible on stuff in kitchen sink disposal.

Klem 1, the current plumber identified the bellies by snaking and having a camera on the line. I have the camera recording and written report with the measurements of how long each sunken section is. You can see where the pipe fills with water at 3 places along the way. One of the bellies is pretty sunken resulting in it being almost full wtih water. Then they jetted to get everything cleaned out and buy us some time to figure out what to do.

It's a slab foundation. I'm quite distressed by this news and just am not sure how to proceed. Is tunneling to access the lines the only solution? We have a large family and people over here all the time, so we need to fix it one way or ther other.

In the meanwhile I am just asking no one to use the one bathroom that gives us the most trouble.

Just to be clear to anyone else reading this: Sewer lines need to gently slope so that the water carries the solids to the main sewer. Too shallow and the solids will settle out and not be carried by the water. Too steep and the water will run off, again leaving the solids behind.

What's happening here is that there is a bow in the line that is allowing the solids to settle out - eventually causing the sewer to clog. Jetting it clears that away temporarily.

I would look at all of your options for re-routing your sewer line. I would also check your homeowner's insurance to see if it's covered.

"Too steep and the water will run off, again leaving the solids behind."

While the argument about this ancient belief continues, the NC Plumbing Code, which is the IPC with some revisions, does not place any limits on the slope of drain lines other than specifying minimums.For example, a slope of 1/2" or 3/4" per linear foot would comply with the Code.
Physics teaches us that objects in motion will remain in motion unless some force acts to stop them. Can anyone argue that the friction within a pipe with a slope of 3/4" per foot is greater than that of a pipe with slope of 1/4" per foot?
I do not believe that slopes greater than code minimums contribute to drain clogging.
As for sagging drain lines buried under slab house floors, the original builder and plumber are guilty of substandard work. Piping must be properly supported-- period. And in NC, plumbing code violations have no statute of limitations.

Bus Driver:

Okay, that never made sense to me either... so I stand corrected.
I'd never run across it in practice.

The important point though is about the lack of slope causing the solids to settle out. what I"m understanding is that sub-surface settling has caused the plumbing to settle as well. Are you suggesting that piping supported by fill isn't properly supported?

If the earth was loose fill when constructed and not compacted and not supported with sand or small gravel, you could have a point. But if there was sub-surface subsidence that's not the fault of the plumber.

OP: Can you tell us how old the house is and is this an area where there are problems with sink holes and such?

If the Earth under the (slab) house settles enough to permit pipes to sag, I would be concerned about the structural integrity of the house. The cause could be from inadequate compaction at time of construction, which is more likely, or subsidence of the Earth due to natural causes.
Either is cause for concern, the first is probably legally actionable.

The house was built in the 1987. We bought it in 1999. I am guessing that there has been some settling of the earth under the house which has caused this problem. I don't know if other neighbors have been having similar problems or not. I haven't seen anyone having foundation repair done in my area.

Is the only solution the tunneling?

I'm leaning toward what bus said and would add that a leak in drain or h/c line can have same result. With 3 problems that far seperated leaks don't sound likly and is easy to test.
Add to your options,"pipe busting method". Roto-Rooter is one company that offers it.

Klem, can you further explain your comment? What do you mean "pipe busting method?"

Pipe busting, Tunnel dug to first drain location,main line is cut and snake ran through line to point where main exits slab. Hole is dug where main exits slab,main is cut allowing access to snake. High tinsil cable pulled from exit through main and out of tunnel by retriving snake where busting machine is positioned. With cable ancored to foundation at exit,machine pulls a head through main busting and pushing it aside. Trailing behind head a 4" or 6" polypropilin pipe is pulled into position where old line was before. Depending on distance from edge of slab , plumber may tunnel to some fixtures,cut hole through slab or remove tub to gain access to fixtures and connect them to new line. In some situations it can save enough tunneling to make installing line faster and cheaper. On some larger homes with difficult locations of basins,sinks and laundry, I opted to pump grey water overhead to connect with another fixture which was connected to main. If one is able to get code approval,there are pumps suitable for toilets also. I've never dealt with bellies useing pipe bust,only rotted and/or seperated lines. It may or may not fit your situation.

I had my sewerage pipes replaced last year and now I have a belly can I get the plumber to fix it that had done the job for no charge

You have my permission.

Just links to a "we buy houses" page. Spam.