The hairdresser dyed my hair darker than I wanted

Today, I went to the hair salon to get my hair dyed in light brown tones. I literally went in with a photo to show what I wanted. But during the dyeing process, they said it needed to "wait a bit longer," so I thought it must be a technical thing and didn't want to interfere. As a result, my hair turned out quite dark brown. It's definitely not the shade I wanted at all. I'm really feeling down about it; I want to fix it, but I'm scared that if I dye it again, my hair will fall out. What do you think should be done in such a situation?