Poor Service... RENAULT Branches and HEAD OFFICE

what do you do when head office service is worst than the dealerships? Terrible service from Renault east rand and Benoni branch. From the 3rd service i told them to check the car as it was overheating. they said it came back with no faults but i knew there was something wrong and sent it back now again. They say thermostat needs to be replaced and I'm waiting for a courtesy car for over a week now. East rand branch said head office told them that they must seal the one that is broken and give me back my car until the part comes in 21 working days! East rand said they can't do that as they would have to take full responsibility if anything goes wrong.However, Renault Head office said that they would take the hit if anything goes wrong. its unethcial that there is not one dealership in the country that has a part for the car. Clio 4 was purchased cash with a extended service plan. i am considering trading my car and moving to another car brand that offers a better after sales service.