Automating Two Follow-Up Responses For Customers

Hello,

I'm creating an Automation to send the customer a follow-up message, for when an agent responds to the customer's request, but the customer hasn't replied to the agent's response in 72hrs (calendar hrs):

I have the Automation performing an 'Add Tag' action to nullifying the automation from occurring again if the customer still hasn't responded in another 72hrs. 

I'm trying to create another automation for when the customer still has not replied, even with this initial follow-up message above. However, I'm not sure what conditions will need to be met for another automation to send a second (final) follow-up response letting the customer know that we are Solving/closing the ticket due to no response. This would be for when we've sent this (above) follow-up message, and another 72hrs have passed since the time that the automation above was sent. 

Please advise, and thank you for your time!