The answer I often give the customer: Is it your car or mine? Ah, it's yours is it? Therefore, it is your problem.
However, I can help you fix that problem, but as it's going to take time & time=money (if I'm fixing your car, I'm not fixing someone elses' = earning money).
Then it is up to you to provide the relevant funds to allow me to fix your car.
Obviously, making a profit on the bolt removal would to me be wrong, but covering your costs and helping the customer would be high on my priorities.