Child not wanting to see other parent anymore...

My partners daughter lives with me and her dad full time. She sees me as her mother and I see her as my daughter as I'm bringing her up, she sees her biological mum at a contact centre once every two weeks. She is now saying that she doesn't want to see her biological mum anymore she is only 4 but she is very clever and grown up and knows what she wants does anybody no what to do and if a child has the right to chose? I feel like we are making her do something she doesn't want to by taking her to see her x