PAYE record for options exercised after leaving job

I left my job in 2022. When I left my employment, I had some non-qualifying options and recently exercised them. When I exercised them, UK income tax and NI contributions were automatically withheld by the platform my former employer uses. Since I've left the company, I don't receive payslips or a P60. How can I make sure that the income tax and NI contributions are accounted for on my personal tax account? When I logged in to HMRC's Government Gateway to view my PAYE history, I don't see the withholdings from these exercises in my history. I contacted my former employer to ask for a P60 to account for the tax paid on these transactions but they have ignored me.

Hi,

Your employer may have sent us all of the information you are looking to confirm. Please contact us by webchat or phone, and we can give advice on how to progress the issue with your former employer, if necessary.

Income Tax: general enquiries

Thank you.