What action can be taken for this case

I purchased a new Renault suv, after 10,000 KM/8 Months faced an issue when the coolant leaked, and immediately this issue was brought to the notice of Renault , and a complete change of Radiator was done along with the topping of coolant during the service. However we experienced minor issues after the service such as delayed starting or cranking. Hence soon after 2 months again we went to check up if any battery issues existed for delayed crank starting. It was then that the Renault observed that there existed engine abnormal heat issue and that all coolant had dried up. It was a failure on Renault part of Service not to rectify this problem during the service and intimate us. It was only found coincidentally when we went to look at delayed starting problem. Renault informed that the engine is heating abnormally and the head should be replaced at consumer's own cost. I wonder how it can be justified when their prime fault is in rectification of problem during their service and that their product has barely run 15000 KM and now has engine issues which has caused a lot agony from the day of purchase.This is a case of manufacturing defect and poor service by Renault. Had Renault diagnosed this problem before a lot of connected engine parts could be saved , however it delivered the vehicle from service with clean chit and now after 4000 kms from service we as consumers should go to them and find out the car has other problems too..it is unfair . What can be done in this matter, ?