Nykaa - Refund not received

I placed the order and later I canceled it due to some reason.

I was told that full refund has been processed however I never received ₹*** I contacted the customer service they provided me ARN but bank says that is invalid and they are not able to track they asked me for settlement copy from the merchant but when I contacted customer service they said they can’t give anything else other than ARN number now where is money and whom I’ve to approach it’s * months already and I’m still waiting.

I shared my bank statement as well for proof please help me and again same problem has occurred with my recent order only partial amount has been credited and still waiting for remaining.

Order was placed on ** February ****