Nykaa.com — Amount not credited in my account

I have ordered watch on 14 June. but not received as showed on site. so i returned the product but till date no refund has been credited to my account. Nykaa told me they have credited amount and provided ARN number but bank is not able to track any payment with this ARN. and Nykaa has not able to provide any proof of payment other than ARN. SO please solve this issue as soon possible. as Nykaa is not able to do anything in this matter. ARN number is wrong as per bank. nykaa team making fool since 15 days as not amount has been credited from their side.