Some time issues
At our office in Granada a vehicle can be picked up or returned from 8 AM till midday and from 13:30PM till 8 PM, every day of the week.
When a rental car is picked up before midday, the client will have to pay rental for the whole day. When the car is picked up after 13:30 PM the client pays half a day rental. The latter does not mean that a car can be rented for just half a day, though.
On the last day of the rental period the vehicle has to be returned to our office before 8 PM if you rent it for a full day. If it is for half a day, then it is before midday.
In other words we work with units of half a day. And please note that our office is closed between midday and 13:30 PM.
In case you want us to deliver you a vehicle or pick it up somewhere (e.g. the airport) the office hours do no apply. But we still work with the same units of half a day mentioned above. Furthermore, we then use moment(s) the vehicle leaves our office respectively returns there to calculate the number of rental days.
You want to know about picking up your rental vehicle and/or returning it at the airport or the border with Costa Rica, have a look here respectively here.