Why do customers still get the same response even though a rule has been set up that automatically emails a specific response under certain criteria?
Since you want to include the response in the email that gets sent to the customer, you must add an additional, specific action in the rule that sends a response to the incident to your end-user. It is not enough to just append the standard response to the incident; you must also send the Response email to the end-user.
Click Add Action and select Email > Send Email Response to Sender.
Note: If an agent sends a response, one message will be sent that contains both the agent response and the rule auto-response.
For example, if agent Smith sends a response and closes an incident, and there is a rule to send a response when any incident is closed, the Incident Solved message template is used. Both the agent response and the rule response will be included in the message. Also note that if the Incident Solved message template is disabled, no response will be sent out, as the Incident Solved message template takes precedence over the Rule Email message template.
For further information on enabling the "Rule Email", see the following answer: Answer ID 5810: Rule Email not sent.