Missing State Pension Contributions

Hi, my husband earns over 50k meaning we are not entitled to child benefit, i was still getting paid my national insurance pension credits as my middle child was under 12. When our middle daughter turned 12 it looks like i stopped getting the credits although our circumstances had not changed and our youngest child was still under 12. After lots of research it looks like as i had never claimed child benefit for the youngest (husband always earnt to much), it meant the system did not recognise i had the youngest child and the pension credits stopped. I have tried to call HMRC Pensions and they have said if i did not claim for child benefit i am not entitled to it. This cant be the correct as i had not claimed child benefit for over 10 years and still got the credits for my middle child as she was once on the system. How can i get HMRC to understand whats happened and correct this. If i had claimed child benefit and paid it all back it would have been fine but as we never claimed it we lost out!!! this cant be correct or fair

Hi,
If you believe you have missing National Insurance Credits from Child Benefit you can fill in form CF411 (periods 6 April 1978-5 April 2010) or form CF411A (periods 6 April 2010-Now) to apply for the Credits.
We will work your application then a decision letter will be issued to you.
If you disagree with our decision there will be an explanation at the bottom of the letter on how to  ask us to Reconsider our decision. Please find links to the application forms below:
Apply for Home Responsibilities Protection - GOV.UK  (CF411) (periods 1978-2010)
Apply for National Insurance credits if you’re a parent or carer - GOV.UK (CF411A) (periods 6 April 2010-Now)
Thank you.