help with replacing modem

Hi.  I am having problems with the modem for our Xfinity Now service. We have had a technician come out and while he fixed it, he said that we will need a new modem soon.  In the month since then we have had repeated outages requiring rebooting the modem.  Today that stopped working completely.  Rather than another technician visit we were hoping to get a new modem shipped to us.  Thanks