Renault in Tokai - lack of assistance.

My car went in for its 90000km service. 2 weeks after the service all the same problems appeared. Messages on the dashboard said check the vehicle, check the braking system and the car was struggling to start. I went back to Renault and said I had to book it in. Only late that day was I told the car was not going to be ready. Unfortunately I was informed late in the day and was unable to get to work and lost the pay. The following day I go and collect it and they say its the battery that is not charging and I don't drive the car enough. I drive a lot. The next day all the messages appear again. They then give me a call asking me to rate them, I refused to rate them the car is still not fixed. They said the service manager will contact me. A month later and I am still waiting. I went on a long road trip and during the trip the service light came on. 2 days ago the petrol needle is faulty, it moves continuously up and down. I phoned Renault on Friday 4th September 2020 and spoke to the service manager and was told that they don't have my vehicle on the system. I will have to book the car in. That means again it will impact on my work. At the moment I am driving an unreliable car and I don't know what more to do.