They were supposed to quote me before opening the car i can't afford R223000 engine

Took my car to them now they changing prices and they don't want to put it as it was. Cos we agreed on if warranty don't pay i must pay R3100 ,now they say for them to put it back like it was R35000 . But not fixed, they first say one cylinder and one injector is the problem my car was loosing power now the say the engine replacement.