I'm sorry to hear this Zulfica, but you have to also consider that the seller may have been 100% genuine with you and had not known the car was dodgy either! The turbo may have been working up until that point - did you properly test drive it?
Can you imagine selling a car to someone in good faith, then buyer turns up on their doorstep demanding the money back and calling the police? Would you answer the buyers calls?
'Buyer Beware' - Always check the car before you buy, not afterwards.