Free Wifi Extender

On May 26 I received an email stating that I was eligible for a free Wi-Fi extender. I still (June 6) have not been able to redeem the extender. The message I get is "Sorry, this line of business is not currently available due to a temporary error. Please try again shortly." I have talked to several people at Xfinity plus made a trip to the store in my city. Everyone just gives me someone else to contact, and no one has been able to assist me.  Can you help me in receiving this free extender. Thank you,