Punjab National Bank [PNB] — transaction dispute or charge dispute

Address:

211011

I purchased lg g3 plus mobile phone ₹15950 from amazon on 09/04/2018 and done full payment by debit card but order was refunded on 03/01/2019 and now amazon is saying that refund has been send to bank. So contact customer service and file charge dispute they had given me a no. Refund reference number : 75503729004025919426107
But customer service is saying they can file nothing like charge dispute and can only check if money came to your account or not.
Same behaviour by branch also.
Don't know what to do