How do I complain about UPI refund?

You can complain about a UPI refund starting with the app you used for the transaction. If the issue is not resolved, contact your bank with transaction details. Unresolved issues can be escalated to the Reserve Bank of India (RBI) Ombudsman or the National Payments Corporation of India (NPCI). The NPCI's toll-free number is 1800-120-1740.