Discrepancy between SA302 and TYO 2020/2021. Class 2 NI seems the problem? Help please

Hi there, I recently applied for a mortgage and it turned out that my SA302 and TYO for the year 2020/2021 don't match. I have been liaising with HMRC for a few weeks now and they deny any issue, But there is a visible discrepancy between the two docs of £158.60 (Class 2 NI amount). The full Tax return matches the SA302. I paid the amount of the TYO which includes the extra £158.60. I checked my Class 2 NI contributions and it says the year is full, although both my tax return and SA302 say Class 2 NI due £0. I have income from both self assessment and PAYE so I assume my PAYE income and tax paid covered the yearly Class 2 NI contributions. However I checked other years (I always have a mixed income of self-employed and PAYE) and the Class 2 NI amount is always there, but for 2020/2021 is £0. And it should have been £158.60, the discrepancy amount. My lender wants it rectified and HMRC told me they would send me a letter over three weeks ago explaining what the issue is, but I have received nothing to date. I rang to see if they could upload the letter in the message facility on my Gateway page but when I rang again they said they see no issue with my documents? I feel I may loose this mortgage now as well as the property. Can anyone suggest anything? I am feeling extremely frustrated. I already spent countless hours queueing and talking to HMRC but haven't got to the bottom of anything.

Hi,

You will need to contact the Self Assessment team.

Self Assessment: general enquiries

Thank you.