no rewards after i finish my Diploma

I registered at Damelin correspondence college in 2012 Dec for Diploma in logistics and supply chain management,i wrote my last exam in 2015 June and they promise to send me my award(Diploma) by Nov 2015 to date I am still waiting and they are no longer responding to my e-mails,Please help me to get my Diploma since i do not owe them anything.my student number is 411944,Regards Dolly ***