A bit harsh yea (and sorry for that) but I deal with this kind of stuff daily and I guess I'm just pretty jaded at this point - same BS over and over. Contractors are (for the most part) all the same - lots of bravado, tough talk and machismo (which they try to pass off as "expert knowledge", which actually works on some people), coupled with a distinct willingness to screw over their own mothers for a buck. There are some great ones who truly embody the term "craftsman" or "tradesman" and who are genuine gentlemen and who care about their long-term reputations but they're outnumbered 10-to-1 (maybe more like 50-to-1 for some trades) by the unscrupulous doofuses. It gets tiresome after a while.
Anyhow I hope you get good resolution to the issue at hand - in the absence of actual testing data I'd say your best bet is to plan on a full replacement. It's possible that's overkill but for a small-ish installation the cost of professional testing and analysis (at least $3k-$4k I'd think) might bring you right to the cost of a full replacement anyway, even if it were to find that a less invasive method might work.
I hope it works out well and it's the end of your problems. Truly. Sorry for my start-of-week, pre-coffee cantankerous tone before.
