Her base is a light higher than a level 3 though??? Her base is a 6-7. So obviously 20vol is the correct one to use there. Do you know anything about the levels and how they work? I assume you do being a hairdresser but it sounds like you don’t calculate what developer you need and you don’t take into consideration the starting level and the level you’re trying to achieve? You don’t just smack on 20vol on everyone because it has “worked” before?? You look at the starting level, and what they are wanting to achieve and then that will give you what developer you need to use. So starting level 4 and they want to be a level 7 that’s 3 levels of lift required meaning you would use 9% (30 vol). (I’m also a hairdresser...)