Well, what got you to that position? Undo it. (A piece at a time.)
However, I side with briggidere in that this 'problem' is best handled by adding bodies, outsourcing, selling the lead or whatever. I am, of course, assuming that business success was the original goal. While I can't think of a viable alternative reason for putting up a business web site, perhaps that wasn't actually the goal.
I did a site for a guy who had been goaded into putting a site up. He didn't actually want to grow his business beyond the two-man stage. This is a formula for serious aggravation especially when I started getting page 1 SERPs and he decided that he wasn't getting enough calls to know if the site was working or not.
It is frustrating. Why am I even here to work on this? "Selling the leads" would seem to be perfectly logical, but that's way out of the realm of comprehension for this person. She'd rather delete the emails into cyberspace.
Change all of the page titles to "Welcome to our site"? Once the lead count goes to zero and your boss realizes that too many leads isn't a valid problem to have, change them back and wait for search engine love to return. Have to agree with topr8, it's easy to stop ranking. Coming back up when your boss realizes that it swung too far the other way... not quite so easy after having taken steps to ruin your SEO.