Reviews are very important to such a company. I would advise filing a complaint with the BBB in your area as other have stated, along with sharing your experience on their other pages like google, facebook, Angie's List, etc.
Here are a few ideas....
Did you do diligence to see who you were dealing with? Was the roofer licensed or required to be by the state or local unit of governement? ? Was a permit pulled and the job inspected by a building officia/ when completed? If not call your local building official and have them come out to look at the job? The roofer may be in violation of the bullding codes and be subject to disciplinary action by the state. I would check all these things before you proceed with a lawyer. Last if that contractor is not established, he won't have the money to fix it. But if he is insured you may be able to go after his insurance company. So aways ask to see a license, insurance and work comp certificate when dealing with any company and find out how long they have been in business prior to signing any contracts.
Michael,
Eric pretty much nailed it.
It is not usually worth it in my opinion and especially given the nature of most leaks and the condition of most sheathing.
Roofs aren't cheap so I think the math usually plays out that the full tear off is a better idea based on the fact that you get a better install and will likely have a roof that will last longer.
WoW Home Solutions