Work trying to force me to work extra hours

[Modernbaby]

I work 34 hours a week over 4 days, I have every Friday off. Work are putting pressure on me to work Friday evenings as extra to my 34 hours a week. So far I have said no both verbally and written however they are now seeking advice from the legal team. Recently a co worker has been forced to change their shift pattern as they were faced with redundancy/no having their contract renewed if they didn't.

I don't want to work extra, I rarely take overtime. I don't have childcare for Fridays and I don't want to find a different or another child care provider. For some reason my work are under the illusion that as my DD is now 12 that she can be left on her own.