CF83 Form submitted by recorded delivery, No showing as Received on Gov Gateway

Hi - I submitted a duplicate completed CF83 Form by Post Office recorded delivery on 21st October 2023, after I was informed to do so by a NI Helpline agent (on 0300 200 3500) following my initial CF83 form (sent on 26th july 2023) not showing as received on the Gov Gateway and as stated by the NI Helpline agent. The Post office, recorded delivery tracker web site did not show the CF83 form (sent on 21st Oct 2023) as delivered. Therefore I followed up by phone with the Post office - they stated to me that the HRMC @ PT operations North East England, BX9 1AN will not sign for receiving recorded deliveries from the Post Office - this is why it was not showing on the Post office delivery tracker. Why is HRMC not signing for recorded delivered letters? Especially when they state to send CF83 form by recorded delivery. Additional why is my submitted CF83 form (sent on 21st Oct 2023) is still not showing as received on the Gov Gateway - what should I now be doing to verify its receipt by HRMC @ PT operations North East England, BX9 1AN?

Hi Paul Bonner,
HMRC do receipt letters sent as recorded delivery and sign for them.
We receive many letters daily in this manner.
When letters are received, we scan them to be digital and they are then listed under their unique identifier such as a National Insurance Number.
As we receive vast amounts of letters daily at HMRC it can take 4 to 6 weeks for a letter to be processed onto our systems.
On the second letter sent to us on 21/10/2023 the six weeks date is 02/12/2023.
Please call/web chat the National Insurance helpline and state “overseas/non-resident” if you contact us to confirm that the letter/s are listed under you National Insurance Number.
Please ensure to mention to the advisor that you have sent the CF83 application form a second time and if there is no trace of your second letter, please provide the advisor of the details you have for your recorded delivery so we can investigate appropriately.
If you have a personal personal tax account,  you can sign in and use the web services to chat to an international caseworker advisor also.
Number - 0300 200 3500
Overseas - +44 19 1203 7010
Fax - 0845 915 7800
Overseas Fax - +44 19 1225 7800
Address
PT Operations North East England
HM Revenue and Customs,
BX9 1AN
Open
Monday to Friday: 8am to 6pm
Closed on Saturdays, Sundays, and Bank Holidays.
Web Address - National Insurance: detailed information
Thank you.