A shop in Kolkata sold me a defective phone and refuses to refund how to file consumer complaint

You can file a consumer complaint before the District Consumer Disputes Redressal Commission in Kolkata under the Consumer Protection Act, 2019. The complaint can be filed online through the Consumer Helpline or in person, and you must provide the bill, warranty card, and correspondence with the shop as evidence. Under West Bengal Premises Tenancy Act 1997, there may be additional consumer protection regulations specific to West Bengal. The Commission can order replacement, refund, and compensation for deficiency in service. If the District Commission does not give a satisfactory order, you can appeal to the State Commission and subsequently to the Calcutta High Court.