H and R block did not include a tax deduction on my 2019 taxes

I paid an H and R block professional to do my taxes In 2019 and just noticed they got me all the child tax deductions except for the young child tax credit! My daughter is 2 years old and I've seen that u can get up to a $1000 back if she had imput the information for it! What can I do? Can they be held responsible? And can I fix it?