Gary Perrin

Can anyone help, I am English I was born and lived in Aylesbury Buckinghamshire and worked until I was 30 when I moved to Australia. I am now 65 and I have a private English pension which matured at 65. I need my NIN to claim this. I have rang and have been told they have no record of me. So 3 months ago I filled in the form on the uk gov website and sent it in to the address on website along with copies of my birth certificate and license. I have rang a few times to find out if they have received it or any updates and I am told they can’t help as that’s another department. The operator said she will get them to call or email me. They haven’t called and it’s not good enough. Is there a way to talk to someone who can help me.