Application to register for Self Assessment rejected

I have applied to register for Self Assessment for 2023-24 on 21 September, 2024. Today I received an email informing me that my application to register for Self Assessment has been rejected due to "personal details not matching HMRC records". I followed the advise in the email and after checking, suspect that the HMRC system has messed up my first name, my first name is "Dai Ming" but the system only took "Dai". My enquiries are as below: 1. Since the deadline for application to register for Self Assessment 2023-24 is on 5 October 2024, can I still file another application now and will I be penalized, given that the error has been a technical one that I have no control over? 2. How do I correct my first name in the HMRC database - I have not changed my name, so I am unsure if correcting my name by informing HMRC "I have changed my name" is the correct approach, or if doing so would help at all, as I would still input "Dai Ming" for my first name and the system might still mistook it as "Dai".

Hi.

To allow us to update your record correctly and confirm this correction, as well as register you for Self Assessment, contact us by webchat or phone via:

Self Assessment: general enquiries

Thank you.

Hi. I have already notified HMRC via the personal tax account online platform using the "I have changed my name" option and is currently awaiting feedback. Is this also an acceptable way or do I still need to call the Self Assessment team? Last time I tried webchat the advisor was not being helpful. Thanks in advance.

Hi,

If you have updated the details online then you do not need to contact Self Assessment as the online update will also update your Self Assessment records. 

Thank you.