"Address provided does not match our records"

My self-assessment application was rejected: "We are unable to process your application because the address provided does not match our records." I entered my current address on the form, so I'm not sure what to do and why the records don't match. I then tried to change my address by updating my profile, but with the move in date I entered, it said "The date you entered is earlier than a date previously held on your address record." So it would not let me update. It then said to contact HMRC to update the address, but when I clicked on the link, it sent me to a page that then sent me back to updating my address on my profile, which did not work. How do I resolve this?

Hi Sarah,
We may need to confirm the update of your address on your record, and give you further advice on how to proceed.
Please  contact us by webchat or phone here to allow us to do this:
Self Assessment: general enquiries
Thank you.