Parker and Son's Plumbing. Need Advice!?

Recently my water main (that runs from my front yard into the house) burst; without thinking we called the nearest plumbing company and that's when we landed on Parker and Son's. When they came they'd estimated the work to be around 300$-400$ (which I guess is somewhat reasonable). But after a half an hour later and some grunt digging, our plumber told us that the price would be instead about 700$-800$ because he believed the pipes were deeper than expected, and as a result, he would need to come back the very next day with another plumber/technician at hand. The next day (being today), another plumber comes and tells us that the price of it has been once again hiked up to about 1200$ because with his experience and plumbing prowess he knows for a fact that the problem lies beneath the cement ground and that the only way to fix the pipes is to break cement grounds next to our house. What do you guys think? The plumber also forcibly insisted that we replace the old pvc pipping system with a copper system for another 1600$ (making the total estimate around 2800$). Does this sound like a good deal? One thing I've noticed with my plumber is that he's always tentative to change his price range. What I mean by that is, he initially charged us about 195$ for the work he did yesterday and the standing around he did today. But because my mom wasn't satisfied with that price, he "made" a 5 second call to his company and told us that he misunderstood his boss and that the price was now 130$. As of right now, my mother is bringing in a second opinion, hopefully this guy's estimate is more reasonable. One more thing, do you guys think home insurance would this kind of stuff? Update: I tried calling the City and they informed us that they're not responsible for the problem we're having (specifically because of the location of where the problem exists). As a result, we called up a self-employed COMPETENT plumber and he managed to find the broken pvc pipe in a matter of minutes (and no, the problem did not lie under the cement ground). The charge for the job will probably be around 400$, perhaps even less if he can get the job done faster. The downside is, with the first plumber we called, we already paid about 130$ for the crap of work they did yesterday and standing around they did today. And if we total everything up, it's going to cost us at least 500$.