Automatic Responder after x hours of no message/answer from our org

So I need the following logic:

• Ticket is created -> if no one in our org did answer to this ticket after 6 hours, the requester should get an automatic message
• Ticket is updated by requester -> again, same logic as if the ticket is newly created, if there is no answer from our org within 6 hours, the requester should get an automatic message. So an automatic message can theoretically occur once after each message from the requester.

In both cases, if someone from our org answers the ticket within these 6 hours, no automatic message should be sent to the requester. Also if the requester sends a message and sends another message after 3 hours (with no answer from our team in between) he should get an automatic message after additional 3 hours of no answer from our team, so 6 hours in total after his first message.

In short words: If someone sends us a message and doesn't get an answer from us within 6 hours, he/she should get an automatic message

Thanks.
Best regards.