Former adjuster here, handled thousands, upon thousands of totals in my career...
1. Make sure to ask for the actual evaluation that the insurance company used to get the value.
2. Review the evaluation to verify the following are correct.
-mileage
-trim level
-options on vehicle
-and here is the big one...check the "condition ratings" the insurance company rated your vehicle , especially if they use the company CCC. Insurance companies love to rate the pre-loss condition of your vehicle as "average", where every comparable they have listed is rated as "dealer retail" condition, which adversely effects the value of your vehicle since they are saying every single comp listed is in better shape that your car, which is laughable, just another way for the Insurer to skim $$$ off the settlement amount. The evaluation report should be detailed to advise what condition category is warranted on the pre-loss condition of your car.
3. If you had any recent major repairs done to vehicle, send in receipts to adjuster so he can submit to evaluation service. It wont add dollar for dollar, but every bit helps.
If all else fails from above, you do have an appraisal clause in policy as others has mentioned.