Airtel — migration from postpaid to prepaid for no. [protected]

I have applied for migration from postpaid to prepaid service on february 22, 2018 to airtel store, at ctm, ahmedabad 380026. However, my number is not migrated till date. I have visited airtel store severel times and called to airtel customer care (121) many times, but they are not giving proper reply. They are saying that service will continue within 2-3 days, but till date my number is not migrated