This sounds so familiar... Here's a story about my 1961 house that is built on concrete slabs. About 18 months ago, we noticed a bit of the hardwood floor was bubbling up. We ignored it. About 6 months ago, our water pressure started to drop and then disappeared altogether. The plumber came and told us that our well pump (which was relatively new) wasn't working. They pulled the pump and the PVC bushing around it was…
Second plumber comes and is somewhat perplexed - he pulls up roots and suspects they've grown into the line. But it's drilled out and should work now. Two days later, the drain backs up again.
Third plumber comes out and goes in from the roof vent. After about an hour of rooting around, his snake pops up through the drain and starts whackkity-whacking around the shower. He's very surprised and a bit sheepish, and suggests there's a bigger problem and we should rip out the shower to have a look at what's under it. Doesn't pretend that he's fixed it. I'm using a different shower at this point.
Fourth plumber arrives to give a second (err, fourth) opinion and is similarly perplexed, saying we likely need to rip the shower up to fix things.
Fifth plumber agrees, and says he knows a guy who can do it.
Sixth plumber is actually not just a plumber, and arrives with a jackhammer, two buddies and a fancy proble that lets him follow where all the pipes go under the house (both with a camera in the pipe and a machine that follows where it goes physically). Scopes things out for a bit, and then goes to town on the other bathroom, eventually jackahammering and digging a roughly 5 foot cube out from under the bathroom.
It turns out when they redid things in the house 15 years ago, someone failed to actually connect the drain from the shower to the sewer, so it had just been draining into the ground. Whoops!
While they were down there, they ran a new sewer pipe out to the municipal line as well. This part was pretty cool. Rather than digging up the whole yard, they just ran a 1/2" steel cable through the old masonry pipe, hooked it to a solid steel cone, and pulled the cone through with a hydraulic winch, trailing some pvc behind it. As it went, it busted apart the old pipe and put a new one its place. All in all a pain in the ass, but neat to see how they approached things.
Aside: I also have and love Amica. They've covered a couple claims for me and have been very easy to work with.