How to completely stop the bot after await response?

I use await response to let my customers ask for particular questions, but after a few minutes of interaction between the human staff and the customer, the bot starts to send messages again, example:
customer: (Await response)...
human staff: answer
customer: another question...
human stafff: answer
customer: another question...
Chatbor: (welcome message)

And we cannot maintain a good conversation between with the customer, because the chatbot starts to chat again.