HMRC Customer Line - No Response after FIVE * 1 hour calls waiting

I desperately need to update my estimated gross income for the 23/24 tax year but I am very unsure and nervous about using the online system as there are items like "non coded income" in my PAYE 23/24 summary. As such, I have now been trying for FIVE consecutive calls, each time for more than one hour, to get through to a HMRC customer service person. How can I talk to someone who can help me?

Hi Anthony Papworth,

Our helplines are very busy at the moment.
You can update this through the Personal Tax Account.
If you wish to speak to someone you will need to keep trying to get through:
Income Tax: general enquiries

Thank you.