Hi Chris,
The best way to query your CF83 application is to contact our National Insurance team.
National Insurance: general enquiries
The telephone lines open at 8am Monday to Friday and if you could call as soon after this as you can then the wait shouldn’t be too bad.
If you’d rather write to us to query the decision, then our postal address is:
HM Revenue & Customs,
PT Operations North East England,
BX9 1AN,
United Kingdom
Thank you.