Poor Customer Service

I ordered 5 x Smart Watch Fitness Activity Tracker Smartband Wristbands from Groupon on 27 November 2015. Upon receipt of the goods it became apparent that only 2 of the five were in working order. I sent an email to Groupon requesting replacement and received an email on 10 December advising that I would be contacted within 2 days. I am still awaiting this call. Upon calling 4 times before Xmas I got \we are experiencing high call volumes"after which the calls were cut off. I sent 2 further emails and received no response. At around 08:45"