Angry and disappointed

I am not sure what we are paying for if no one bothers to respond to emails. I was made to drive a car 3 months after paying for a part and not told that the part was not replace by Megan Bedford branch manager. What is worse is that I laid a complaint literary a month now and still no one is coming back to me. I was told within 3 days and with email follow up and calls to your complaints department nothing. I need a response please because I want to take the matter further.