Adidas — Refund related issue

I ordered a pair of boots on 10th march and i got it delivered on 12th march as the product was a big in size for me i ordered returned it and I haven’t received any information regarding the refund and i tried calling the authorities multiple times and they said I’ll get a mail regarding the refund to fill in my bank details as it was cash on delivery but I haven’t received any mail from their side and the product has been returned.