# Update User Complaint
source: https://developer.mastercard.com/india-online-dispute-resolution/documentation/use-cases/update_dispute/index.md

The Update User Complaint API updates the user complaint details based on the complaint tracking number. Issuers and acquirers can use this API.

## Prerequisites {#prerequisites}

The issuer or acquirer needs the following parameters:

* Complaint tracking number
* Comment
* Complaint status (optional)

## Sequence Diagram {#sequence-diagram}

Diagram update-dispute-by-tracking-number

#### Execution Steps {#execution-steps}

1. The user sends a valid tracking number and comments to IODR. Note: Sending a complaint status is optional.
2. The IODR validates the tracking number and status, ensuring the comment is no more than 250 characters.
3. If the tracking number is invalid, the IODR responds with an error message.
4. If any of the fields is valid and exists, the IODR sends the updated status and success message to the user.

Note: IODR sends email updates about complaints to the issuer and acquirer.

## Endpoint {#endpoint}


API Reference: `PUT /complaints`