What action can I take if company denies work-from-home during pregnancy?

I work for a recruitment and staffing company, and my role allows me to work from home. I joined in April 2025 and found out I was pregnant in July, which I informed HR about. I requested to work from home for three months, as advised by my doctor, and submitted the supporting documents. After three months, based on further medical tests, my doctor advised against travelling for nine months. I informed the company with documentation, but now they are denying work-from-home and are asking me to apply for pre-maternity leave from the date I informed them about my pregnancy. They said they will grant me six months' maternity leave only from my due date, on a personal note. I refused and asked them to provide this in writing. Please advise.