Hyundai Motor India — Recent engine job done by hyundai official service center

Address:

Wazirabad delhi

On april3rd my car creta 2017 petrol stops working then I contacted to shuban sai hyundai waziarabad they said the car needs engine job to be done after that the car is become as good as new but on 14 june they contact and told me that my car is ready then i pay them 65000/- cash for engine job but after that my car engine is not working properly and and having a very irritating sound and even iam not able to drive it properly after that i contact them Then they are not picking up my phone and behave rudely and now they start saying that my car’S catalytic converter was not working properly so they removed filter form it.
Without my permission how can they do that
I want my money back or else they do the job they pay for.