hworried

I started a job in Dec 2019 and left in Sep 2021. When I received my P45, 'total pay in this employment' was blank and the total pay to date was for the 2020-2021 tax year only. I queried this at the time and was told that this was correct. I had an employment break until June 2022, during which I did about 2 months of freelance. I've just received a tax break through PAYE and a tax rebate via cheque. I obviously haven't spent any of this because I'm pretty sure the calculation must be incorrect. How do I get this fixed? I can't find an email address to contact HMRC and the phone line for HMRC is only open during working hours.