Answers

If actual damage has occurred to the roof, due to hail, there is really no other way to fix the damage, except replacing the roof system.  

Depending on the type of roof that you have, if the damage is minor, you might be able to complete a spot repair, but that also depends on the condition of the roof.  Hail typically falls randomly over the entire roof, so when there is damage, it tends to be all over.  If your roof is older, it might not be in repairable condition, or your roofing material might have been discontinued and have no match available for sale.

I suggest having a Haag Engineering certified roof inspector or a structural engineer evaluate the roof and tell you if you have another option.  

Everything the rest said above but, in regards to the warranty: 

Check with your Secretary of State and see how long they have been in business.  If they are giving you a 10 year warranty, but have only been around for 6 months, then who cares?  They won't be around long enough for you to have a warranty issue.  

On the other hand, if the one around for 2 years has been around for 10 years, then they probably know that no one calls them for legitimate warranty issues 10 years later, and simply cuts it short so that they aren't called back to fix work that they didn't do.