Worst experience with the creta

We have purchased Hyundai Creta on 17th February 2016. In the Month of August, we have found problem in the vehicle as the vehicle reading was 9100 kms as automatically coolant was evaporating We handovered the vehicle in the Hyundai Show room in Nalgonda and they had found a defect in EGR valve and Engine Block and they had changed the parts of the vehicle on warranty and handovered the vehicle back on October 1st week at the time vehicle reading was 9476kms. After running the vehicle for 100kms we had found a lot of black smoke coming out of Silencer and pickup was slow and mileage was also reduced and we had called to the showroom supervisor and he asked us to run the vehicle for 5000kms as they had changed the engine block its take time to settle. At the time of reading of 15044kms on 1-Nov-2016, we handovered the vehicle in the Hyundai Showroom complaining about Black smoke, slow pickup and less mileage they had changed the engine oil and filters and handovered the vehicle back to us on 2-Nov-16 saying that the problem was cleared. After running the vehicle for 100kms we had found a lot of black smoke coming out of Silencer and mileage was also reduced and we had called to the showroom supervisor and he asked us to run the vehicle for 5000kms as they had changed the engine block its take time to settle. At the time of reading of 19264kms on 6-Jan-2017, we handovered the vehicle in the Hyundai Showroom complaining about Black smoke and less mileage they had changed the engine oil and filters and handovered the vehicle back to us on 9-Jan-17 saying that the problem was cleared. But the problem continued and in the month of 12-Feb-17 we had conducted one road test with our Creta and other Creta took a small video kept a mail to Hyundai customer care and handovered the vehicle in the showroom and after two days they had called me to take the vehicle as it was ready I had asked them to keep a mail or write a letter Head that the problem was cleared but till date they had not given the vehicle they are saying that they are still trying to rectify the problem.