Wrong name on self assessment

I am a non-resident landlord. When I received the first letter from HMRC regarding the approval to receive rental income with no tax deducted, my full name was printed along my address and the information was correct. However, on the 2nd letter I received shortly after, which was about my self assessment account and UTR number, my first name became two alphabets ( like initials) which was not my initial, but the last name and the address were correct. I don’t know what went wrong and I don’t know how to change my name back. I cannot use the online service the change the details because I don’t have a national insurance number .

Hi Michelle T,
If your name is incorrect and you are unable to amend online then you will need to contact HMRC to review and update:
Self Assessment: general enquiries.
Thank you.