Where can I complain about UPI transactions?

You can complain about UPI transactions through multiple channels. First, raise the issue with your bank or the app provider you used, which may have a built-in support feature. If unresolved, you can escalate the complaint via the NPCI's official website or by calling the UPI complaint number: 1800-120-1740. For example, if you used the Paytm app, you can file a complaint directly within the application.