Adidas — Did not received refund

I had ordered adidas track suit but due to size issue I had returned my order AIN02217733, the mode of payment was cash on delivery. It reached their warehouse and I got a mail that refund is initiated but they did not asked my bank details . It has been more than 3 weeks and I am yet to receive my refund also there customer service is not responding, neither on call or chat or messenger.