Wrong salary and tax reported

My old employer has issued incorrect P45 and final salary figures to HMRC for tax year 2022/23. There has been a calculation error somewhere in the full year salary. I have contacted HMRC twice and sent all the information by post as they requested and they have said get the employer to fill in an FPS or EPS My old employer i have contacted 4 times and they are completely ignoring my request. I am owed tax back for the year What else can I do?

Hi Marlene Connollyowen,
Your employer may now have updated your record with the correct pay and tax information.
Please contact us by webchat or phone here:
Income Tax: general enquiries
We can review your record, and give further advice if this update is still not present on your record.
Thank you.