xfi pods will not stay connected.

I have 3 pods; have been using them for a while.  Lately they will not stay connected.  Have tried all troubleshooting ideas I can find on general internet and Comcast to no avail.  Also have tried the assistant and live phone call with technical person.  No help so far.  One person from Comcast said I need to get new pods.  How long should they last?