customer services

Hi does anyone have an email address for customer services or even better someone who has some authority. I have written 2 letters to Renault but have not even received a written acknowledgement. Did get an answerphone message from customer services asking me to call them to discuss issues raised in letter. Firstly, it takes half an hour to get through to someone, secondly person who left a message was person we were complaining about who appears to be dealing with a complaint about himself. Thirdly I would like a reply in writing so I can then go through it before speaking to someone.