I have a Linksys cable modem (befcmu10) that I bought years ago and I just got a letter from Comcast that says I must upgrade my modem by nov 19 or lose my internet connection. They say its to old and wont work with xfinitys new technology. The standard on my old modem is docsis 2.0 and the new ones now have docsis 3.0.Is comcast pulling my leg on this modem upgrade??.