Lack of response

my wife had what we believe to be a serious concern with Renault, I called their number and got an email address for someone that would then pass our concern to the MD. That email was sent to them on the 18/11/2015, since then we have received no response, no telephone call nothing. I also called the offices again yesterday and asked them to respond, they said they would investigate and come back to me, still no response. feel this is poor service from a major car dealer. Our concern is still there and causing my wife to worry.