Why is my mechanic occupied?

When you call a person or company that provides some service and they do not answer or are unable to help you, it means that whatever the service you are trying to get is not possible for one reason or another.

For example, when calling for a taxi and the operator tells you that there are no cabs in your area, it most likely means you are not near a road where a Taxi could realistically travel to.

The same goes for your mechanic - If you are on top of a mountain or in a submarine or parachuting or just out in the middle of nowhere, he can't bring the car to you, so he will say he is occupied. The other reason could be that you don't have enough money to pay him, so he is unwilling to deliver your car to you. A third option is that you don't have any cars - they have all been destroyed, sold, or impounded.

I haven't actually had all of these happen to me. The dialogue may be different based on the reason he can't help you. But if it's not clear, it should be one of those three reasons.

I found the answer. You need to pay your mechanic $50 daily. when you don´t have $50 at the point you need to pay him, you can´t use your mechanic for a week (ingame time). make sure you have $50 dollars at the end of the day.