Employer imposed Benefit in Kind after termination

Hello - I went through a contentious end of employment with my previous employer in February 2024. They terminated my employment 3 weeks before my 2 year anniversary for questionable reasons. My termination document and my employment contract mentioned that the company owned the computer equipment for the job. On the call with HR where they cut me off, they told me they would be mailing me a shipping label to retrieve the equipment. It never arrived and several months later I find out they are saying the computer equipment has been given to me as a benefit in kind and I'm required to pay tax on it. I have tried to reach out to them to correct the filing and arrange a label to actually arrive at my address to send it. They are refusing to cooperate. I believe they are incorrectly filing a BiK and I should not have to pay tax on it. How do I go about working with HMRC in this error?

Hi,
If you have a dispute with your previous employer regarding a incorrectly filed BIK notification that they are unwilling/unable to resolve with yourself direct,
then you should visit  ACAS
Thank you.