Air India — Wrong Information Given by customer care

On 3rd August I booked my flight from Delhi to UK for 24th September, 2022. Flight no 58G6HW. I contacted the customer care service on the same day before booking my flight to enquire about student baggage allowance. The said customer care told me that a 23kg bag is allowed when you show your student visa over the counter. They did not tell me that the allowance is no longer available as it was post 31st July, 2022.
I should have been informed about this! So that I wouldn't have booked the flight at all. I was taking the flight for the student allowance. I want the airline to allow me the student allowance as it was miss communication on their part.