Employer has not provided P60 and is not responding to any type of communications

Hello, My wife is on maternity leave and has had a horrible experience at her last job. The most recent being, her employer has not provided the P60 certificate and is not responding to any type of communications, she is ghosting her. We contacted ACAS and they said we should reach out to you and provide all the employer's details so you can reach out to them. Could you please advise if that's the case? It's a legal obligation of the employer to provide a P60 Certificate and yet we can't seem to find a way to make her do so.

Hi,
As well as providing the employee with a P60 at the year end an employer should also notify HMRC through Realt Time Information of any pay and tax information relating to an employee.
Without having acess to your wife's record we are unable to check this.
We would suggest your wife contacts HMRC and provide details about the situation/position and they can offer further advice:
Income Tax: general enquiries
Thankyou.