HDFC Bank — GST not refunded on credit card annual fee waived

My credit card was charged an annual membership fee of Rs. 10000, plus GST of Rs. 1800, on 25/5/2022, under ref. no. 19999999982525999629130. The membership fee of Rs. 10000 was reversed on 27/06/2022. However, the GST has not been reversed despite my complaint to the Credit Card customer service. This is most unusual practice compared with other product or service retailers who refund the full value of any refund (inclusive of GST). I request assistance to obtain a refund of Rs.1800.