Nissan cannot fix my qashqai under warranty!

Car taken into Bruma dealer on 22 October. Its been in for repairs twice now and the same problem still persists. The car has lost all its power. It takes so long for my cqar to pull off in first gear that i even get cars behind me hooting. The engine light keeps coming up. Nissan head office guaranteed me that they would put a specialist on the case, and even after all this trouble i still have a vehicle that i cannot drive! Im going on holiday in two weeks time and i cannot trust that my family will get there safely in this car. Ive has such a bad experience with this car. A few months ago i reported the brakes were failing. They checked the car and told me they could see nothing wrong and that i was safe with the car. The brakes were not working properly i could tell! I almost drove into a truck on the highway. Only then did they listen to me and look more extensively into the problem. I still dont feel that the problem is resolved as ive had a few attempts at pumping the brakes really hard! I feel like someone has ****** my money and given me nothing in return for what i paid 100% cash upfront!