Who can i ask for help?

I live with my mum. Two days ago me and my fiance paid her rent for next month. Yesterday she threw my fiance out with no reason while I was at work and refused to give his rent back. We have no written rent agreement with her. She won't let me back into the house when I need to and yesterday installed a chain across the door so my key is useless. I'm so miserable and I don't know who to ring up for help and advice on where to go. I have two dogs. Me and my fgiance gave up our house In norfolk to move to devon with her because she needs an op and says she will need help so we moved in with her.