It depends on what you want to file a complaint against Zelle for.

The most common complaint about Zelle is from people who’re defrauded into sending money to someone via Zelle for purchase of some goods or services and it later turns out that that “someone” is a fraudster who decamps with the money.

If that’s the nature of your complaint, I refer you to the following warning on Zelle’s homepage:

If you don’t know the person, or aren’t sure you will get what you paid for (for example, items bought from an on-line bidding or sales site), we recommend you do not use Zelle for these types of transactions.

In other words, you should use Zelle to send money only to people whom you trust in advance. See Using Zelle® to pay for goods or services from someone I don’t know. for more details. With such a candid and crystal clear warning about not sending money to untrusted people, I doubt if any complaint related to this category will receive much joy from Zelle.

If your complaint is of a different nature, you can complain against Zelle via one or more of the following channels:

  1. Complain to Zelle directly by filling the Support Form on its website. More at Contact Us | Zelle.
  2. Complain to the Bank via whose mobile banking app you used Zelle.
  3. Contact CFPB’s Consumer Complaint Database (Consumer Complaint Database | Consumer Financial Protection Bureau).

Best wishes for a speedy resolution of your complaint.