They put it in a year and a half ago. It is not correct. The insulation hid the leak. One thing for sure is that neither connection is plumb to the unit. So they brute-forced it in there, and now it's leaking. To a layman, that seems pretty obvious. In sum, they did a crap installation job and now they are disclaiming it.
File a complaint with the Better Business Bureau and send them the photos. Usually, they try to mediate a settlement. If they will do it for $100, pay it and call it a day, but make sure they do the repair right. Also, find a highly-recommended local plumber and get an estimate from him over the phone (don't expect him to come and look on a job this small). If his price is reasonable, and you haven't heard from the original guys, bite the bullet and get it fixed right by a good company. Then do your thing on Yelp!, the BBB web site, etc. to the original company. Include as many ugly photos as the site will hold and a notation that this happend after a year and a half and they refused to fix it. They may not be legally-obligated to fix it, but assh---ish business practices are things that potential new customers should be aware of. Because many good guys who take pride in their work would fix it, and they deserve ALL the new business.
All of what I say above assumes that this isn't some old POS pipe that was there previously. That spigot to the right looks 18 months old; the rest of the pipe doesn't. Which may or may not be the result of sloppy work.