How Can Hair Loss Be Treated?

My mother had a colour rinsing (colour fixing) 22 months ago. The hairdresser applied the solution, and told her to keep it on for 40 mins (typically applied for a maximum of 10); throughout these 40 minutes, she had a burning sensation on the scalp, she told the hairdresser but he insisted that it s going to be okay. A month after, she observed some hair breakage, loss and weakening which intensified over the following months. She consulted some experts, and she s been using topical solution (Minoxi 2%), Trimoxi HSN Complex (hair follicles strengthening pills, composed of various vitamins), and a variety of vitamins: B12, C, E, D and zinc. There has been slight improvement, but still, she s struggling with hair breakage and weakening -and to mention that her hair type is weak originally - which s causing emotional and mental stress. The question is, what scientific and medical treatments or products, be it vitamins or solutions, to help her solve this issue?