Modem unresponsive

Hi, so I get this problem message on my account. My internet connection has been on and off for the entire day. I had an online agent look into it. They said they fixed my issue, however, my internet keeps getting disconnected and the same message that modem is unresponsive is displayed on my account page. I’m afraid if I get someone to come over to my house I will be charged. I must mention that I fo rent the modem from xfinity.