Baby haircut

I hv repeatedly told mil not to cut my baby hair as I don't believe cutting shorter will help baby's hair to grow faster and I love my baby hair. My husband and i weren’t planning on cutting her hair for a while. Until yesterday, I saw a change on my baby hair and it looks awful (uneven cutting). I don't wish to confront my mil cos I knew she will deny it...but I'm very upset by her action. What should I do to avoid this to happen again?