The treatment itself I would give 3 stars, but the customer service was appalling.
Several foils had smudged, leaving me with a lot of horizontal stripes around my parting. I made an appointment to correct this. When I showed up, staff had no idea I was coming, and nobody who could speak English was there. Another customer ended up translating for me (to the hairdresser who had botched my hair in the first place), and I was rudely dismissed. Do not waste your time and money.