Fail to get an UTR number for a housewife with income from bank interest

We are a family from Hong Kong and have migrated to the UK since Dec 2022. My wife has been a housewife (i.e. no salary income) before and after arriving to the UK till now. She got some interest from the bank account but within the interest tax allowance. To apply for split year treatment for the time in Hong Kong and in the UK respectively, she filed a register to get a UTR number in Sept 2023. However, she got a return email from HMRC saying that "Unfortunately we cannot confirm your identity as the information you gave us does not match our records". She then checked once again her information in her government gateway account. All the information is correct and she has no idea what information does not match HMRC's record. Could you advise how she can proceed so that she could get an UTR number? Furthermore, as per her case, does she need to apply for split year treatment and submit self-assessment form this year? I think she needs a real person from HMRC to sort the things out. How can she get real-person help from HMRC?

Hi lwkahy,
Your wife would need to contact HMRC:
Self Assessment: general enquiries
Thank you.