"We didn't receive your tax return on time"

I've recently received a letter from HMRC about a £100 late fine about a self assessement tax return that I need to pay for the tax year ending 5th April 2022. I have never been self-employed, and always have paid PAYE tax. I am trying to contact them on the phone however have been on hold for over an hour with still no answer (This is ridiculous). I have done their self assessment online and that confirms I do not need to send a tax return myself. The Gov.UK website also can not confirm I am who I say I am, so I can not appeal the fine online. Is anyone having any related issues or dealt with this before?

Hi,

If you are unable to verify for the online account to submit the form, you will need to keep trying to contact our Self Assessment team or write to us.

Self Assessment: general enquiries

Thank you.