I coloured one of my customers hair last month she had very dark hair and wanted it lightened I explained it wouldn't be as light as she wanted it first time and it might feel dry so to use regular treatments etc. I used 20vol and bleach and checked them every 10mins. The hair was fine no problems at all. She has now messaged me 4 weeks later saying another hairdresser has had to re cut it as her hair was extremely dry and brittle. This wasn't the case when she left my salon and now she wants her money back. Should I give her it back knowing it's been 4 weeks and another stylist has touched her hair?