BMW India — Defective car supplied

Sir,
We had purchased car in April 2021 520 d series car no wb12BE 9898
From purchase date till now car had gone to workshop for 6 -7 times and problem is not solved . They always give assurance that this problem will not arise again
And this osl agents while selling cars gives assurances that alternate car will be given but nothing as such happens
Out of 730 days my car is in your workshop for 155 days but no outcome
We feel that this is defective car and your agents selling this car is waiting for warranty period to be over
We would like to say that if this car is defective then kindly replace the car.
We want written confirmation from you and your agents that this problem will not arise in future if it arises then you had to replace the car with new car
According to your agents workshop car had been repaired but we will not pick up the car until and unless we get assurance from both of them