People will need a LOT more information to help. How old is the car ? What mileage is on it ? What mileage was on it when you bought it ? How much did you pay (roughly. This can be important as to whether you had 'reasonable' expectations). When was it last serviced BEFORE you bought it ? Have you had it serviced ? If so, when ?

"The onus is normally on you rather than the trader to prove a claim (that is, to prove that the vehicle is faulty in some way). However, the law states that if you are claiming repair, replacement, full or partial refund within the first six months of ownership, the onus is on the trader to prove that the vehicle was sold without faults when you bought it. This is called the 'reversed burden of proof'. After six months, the burden of proof reverts back to you to provide evidence to support your claim that the vehicle was faulty when it was sold."

(From tinyurl.com/kmkoy92)

However, failure of camshafts and other parts may put you in a good position. This sounds like something major.

As has been said, more details would be helpful.