To the best of my knowledge the service centers for Toyota are "first come - first served" basis. So there is no need to call or make an appointment. Just be there really early in the morning (before 6 am) or Try the afternoon shift which starts receiving cars at around 4 pm. (again first come first served). So for the 4 pm try to be there around 2pm to 3pm to guarantee yourself a spot in the workshop.

Now if your service demands major work or tools (facing any problems with a new car??) you could be asked to go to Industrial Area and take the vehicle to the main workshop.

Regards!!