Missing NI payments 1981/83 worked as civil servant

I am due to get my pension this month. Even though I have worked for 45 years I am told I will miss out on getting full amount, as there are shortfalls for years 1981-1883 during which time I was working for HM Diplomatic Service. How can the Government not have paid my NI? I worked for them in this role from 1979-1989. Also HMRC assigned me two NI numbers with different endings (A and B). I have checked this with them - they say it doesn’t make any difference….

Hi Caracas80,
I note that your National Insurance account does not reflet the amount of contributions that you’ve paid for the 1981-1982 to 1982-1983 tax years.  
If you have your P60s for this period (or your last payslip for each tax year or if not any payslip) then please let us have copies and we’ll be able to trace for any missing contributions and put them on to your National insurance account.
Our postal address is:-
HM Revenue & Customs
Individual Caseworker
PT Operations North East England
BX9 1AN
Turning to your National Insurance Number.  The letter at the end of a National Insurance Number is not used any longer so as long at the first two letters and six numbers are correct then this is fine.  The end letter was used prior to 1975 when we went computerised and was used to stagger contributions coming into the National Insurance Office which had to be dealt with manually.
Thank you.