Poor poor customer service

I bought a car on the 6th of December 2021.The following week it shows on the screen oil senser need to be changed and I must consult workshop.The max were not the same.The money I paid was not the same as the advertised.I don't owe them even a cent.It's been 4 weeks now with out a car.They did not even answer my calls.It's affecting my health,my family and my work.I'm so frustrated and desperate for help.