Need to Update National Insurance Home Address - Cannot verify id with 2 forms of UK id

I emigrated from the UK decades ago and need to update my National Insurance with current address. I have only my National insurance number and I cannot sign up for the Government Gateway id because I do not have 2 pieces of qualifying UK id.to complete the signup. Alternatively, the online information I find advises me to write which I did over 4 months ago asking for this to be done and or to contact me with the required forms or process. I've heard nothing as yet. Is there a form I am supposed to complete and send in with copies of id etc. with a letter? All I sent was a letter as there is no information available online as to what the letter should include. Thanks.

Hi UKGOVESS,
Our International Teams are currently dealing with queries received in February 2023 so, unfortunately, there will be a delay of about 43 weeks from the date that we received your query. When they do deal with your query they will update your National Insurance account as required and provide you with any information that you have requested in your letter.
Thank you.