I called Comcast when I was to exchange my modem. The rep said I could exchange at this service center. The girl was more than nice when I arrived...but, exchange they do not do here. You can bring in your old modem, but that is it. Maybe you should reword what your definition of "exchange" really means. I think it may have been confusing to your Comcast rep. It may have been something they did in the past, but not now. At least not with modems..but remotes, etc. There is no direct number to call them ourselves. My stars rate this service center, not the inaccurate advise from the rep.