I took my mini for service and was told that i had...

I took my mini for service and was told that i had to replace a water pump. I did give consent to replace it and when i came later to collect the vehicle, i asked to see the leaking water pump that was replaced. i was told if i want to see that part i should pay for it. I paid to replace the water pump and how is it that i should pay again to see the replaced part?

Bad service!!!