Myntra.com — Aristocrat COMMANDER trolley/ Refund not received

I have placed order for Aristocrat COMMANDER Camouflage Print Expandable Medium Trolley Suitcase on 28th June. I have cancelled the order due to late delivery on 8th July and refund was expected to be credited by 18th July. I have made payment via UPI and refund was initiated for UPI.
I have connected with Myntra help line multiple times that I haven't received refund but they only provide me with reference number but I am not finding any transaction with this reference number on my UPI account (Paytm).