Since I told them I was pregnant, they have reduced my hours from 30+ to 7 hours a week

I have worked at a cricket club for over 4 years. Happily acting bar manager, seeing events from start to finish/working all events and dealing with staff. Since i told them i was pregnant in March, they have reduced my hours dramatically from 30+ hours a week to 7 hours a week. I have taken up a grievance with the club chairman and my line manager, but they have told me my grievance is not good enough for them to respond to or for them to even hold a meeting with me. They have made it very uncomfortable for me to attend work. The atmosphere is very difficult as they choose not to speak to me. I have received nasty emails weekly from March up until the present day. All of this has been extremely upsetting for me as I have enjoyed my past years there.