Can't access account to file Self Assessment due to a new phone number

I can't file my self assessment as I have a new phone number and therefore cannot get an access code. There are zero options to add/amend a phone number or verify through alternative means - the option for "change how I get my access code" only leads to a page with the online services helpline, which when called and following the prompts (which specifically include the issue of having a new phone number) gets cut off, without even the option of being put on hold. The fact that there is no other way of receiving my access code when you hold so many other identifying pieces of information and when it's impossible to get hold of anyone by other means is ludicrous. I know I'm leaving it last minute, but this shouldn't be an issue in the first place.

Hi,

I apologise if you are having issues getting this resolved. If the option online does not allow you to reset the number you will need to try our Online Services again.

Technical support with HMRC online services

Thank you.

Hi, did you find a way to solve this? I've been trying calling the helpline for days but can't get through. Thanks

Hi CarloA,

Our helpline has been busy however it is our Online Services Helpdesk you need to contact if you have been unable to reset your new number online.

Technical support with HMRC online services

Thank you.