In all cases where it shall appear that the age of the person insured has been understated in the proposal, declaration or other instrument upon which a policy of life insurance has been founded or issued, then the amount payable under the policy shall be such as the premium paid would have purchased at the correct age; provided, however, that one who, by misstating one’s age, obtains life insurance not otherwise obtainable shall be entitled to recover from the insurer on account of such policy only the aggregate premiums paid.