Unprofessional customer service

Highly dissapointed with the service I have been receiving with renault dtm strand ,wher I purchase my motor vehicle 3years ago .took it in for service to find out my service plan has expired long story short when u call they ask u for ur details aswell as kilometers and vehicle registration number and for wat service are u coming for . Do not understand why ask all the information and book the car in that morning to be called hours later with information that service has expired ,took it up with manager juandre and then decided to iether trade it in or extended the service plan . Went in to renault to have a look at wat I can trade in and spoke to mr steyn who was going to assist me with a deal and get back to me .after weeks not a call from him which I decide to call abd ask for another sales person to help as I need to decide to iether extend the service plan or trade my car in . Been help quick by new sales lady by the name angie who then heard a noise on the steering wheel aware of my story but tht my car was underplates warranty and should bring it in to them I called the service department on Tuesday and again mentioned to them about the service but tht I was adviced to bring it in as it's under warranty stil the sales man chad took my details and book the car for Friday .only to be called once again to be told now that they cant do it as the service plan is not up to date ,now wat has the service plan and the warranty of the car got to do if u have both on ur vehicle when u buy it. But not just that your time waisted to get ur car on time and you mention all necessary details to sales staff and this is how you treated again .I mean really if you could just assist me with my request asap so that I can make a decision as to wat to do but this bad service can not go on as I feel now ill never want to put foot in another car just cause of the way I'm been treated by them .Hope the right people get this message. Or would like a call from the service principle to resolve this matter .