Lost national insurance number

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.

Hi,
I am not sure which form you have already completed, but the correct form for you to completed would be a CA5403 - Get your National Insurance number by post
The current timescale for receiving a response to this form is approximately 2 weeks.
If this is the form that you have already completed, I would suggest that you call the National Insurance helpline again and ask for an update to your application (unfortunately, a call back cannot be arranged on this forum).
The number to call is +44 191 203 7010.
Lines are open from 8am to 6pm, Monday to Friday.
If you haven’t completed this form, please complete it following the instructions in the link above. 
Thank you.