I NEVER look at the full repairing cost being charged, I spread the repairing costs over its estimated useful life.
This is how I would have looked if I were in your position.
Amount charged / estimated useful life
Amount charged = 18000/-, estimated useful life = 12 months.
18000 / 12 = 1500/- per month is the cost of repairing this, provided that the work done lasts 1 year, nothing much at all.
Since repairing done by Mr. Afzal professionally, so it will last much longer than that depending upon road conditions.
Can't you bear 1500/- per month expense to save yourself from this car headache?
Looking at the parts replaced and the condition of car you mentioned, you are charged fairly.