Bad service

On March the 30th I went for an eye test at Spectrum optical in Uitenhage. I have ordered a pair of rayban glasses and 2 months after I still have not received anything from Spectrum. My medical aid has informed me that Spectrum has now claimed for the glasses which I have not yet received. I have been calling Spectrum more then once to enquire about my glasses and all they do is asking for my contact number so that they can call me back which they never do. They never return my calls and have no ETA as to when I will receive my glasses . Is there any way that I can have the payments reversed as I do not want to continue doing business with them anymore. Any advise as to how I can approach this?