Faults on the car...repairs taking over 3months

bought a black merc 160,onli to find it had a lot of faults.Returned it to the seller, in Dec,who said he will sort it out.Hv gone to his shop,the car is stripped,no evidence that it will be repaired.Hv foned the seller on several occasions,he ignores my calls,if he answers he lies.Hv asked for my moneyback,he refused....i really dont know what to do now.I really need help