This is not only the case with IDFC but banks like Standard Chartered too, this is the second time I need to reach out to Stan Chart to get my spend based reward voucher. Again their CC executives are clueless about the spend based offer and not paying heed to my request despite attaching the offer details and screenshots within the emails.
Never faced such issues with HDFC and Amex, always received vouchers from their side without even me poking their customer care executives. Amex goes an extra mile when it comes to customer delight, recently got a 1500 voucher from their side which I almost forgot after making the necessary spend. But Amex being Amex, they didn't cut the corners and sent the voucher timely.