Mismatch of the records

I have been trying to register to HMRC services but cannot do so. I put all the details such as name. DOB, NI number, government gateway number etc. correctly but keeps getting this message “The information you gave does not match our records”. I tried calling the numbers provided on the website but of no use. Can you please help me out in reaching the right place to raise this issue. Thanks in advance

Hi,
I am sorry if you are having issues registering for Self Assessment.
If still not able to register online then you will need to contact HMRC direct to review Self Assessment: general enquiries
Thank you.