Letoval is the brand name of a drug called letrozole allowed to be used for breast cancer in post-menopausal women only. Nowhere in the world, including India, can it be used for any other purpose. Its side effects are numerous and include ovarian tumours, liver cancer, heart attack, paralysis apart from toxic effects on embryos and foetus. It can also cause malformations of fetus.
Letoval was being actively and illegally mispromoted by the manufacturer for infertility. The company was reprimanded by the Drugs Controller General, India (DCGI) and apologised for its actions.
Under Indian laws such as Drugs and Cosmetics Act and the Indian Medical Council rules, medicines cannot be used for any purpose other than for which they are licensed. The complaint can be made to the Medical Council of India or a court of law under Indian Penal Code.
You would not be able to file a complaint with the Consumer Court since it will entertain only those cases where some damage has been already been done and compensation is sought.
However, if you have a cash memo from the chemist, then a complaint can be lodged with the Drugs Control Department. As per law, Letoval can be sold against prescription from a cancer specialist only, not a gynaecologist. It is clearly printed on the medicines catch cover.