Does insurance have the right to only fix part of your roof

A tree limb landed on my roof, State Farm only wants to replace or fix part of my roof, about 1/3 of it and leave the rest alone. This would cause part of the roof to be new and the rest to be old and outdated. Anything I can do? I've had a second adjustor come out and they pulled the good cop/bad cop saying the first one gave too much and the last one only would have replaced a few shingles. Am I getting the run around? Or am I basically screwed.