Answer by Japanese teacher
The phrase yoyakushimasu means “to book or to reserve something”. If you conjugate the masu form of the verb to “~tai”, it means “I want to ~”.
In this case, yoyakushitai means “I want to reserve”. Simply add the time and day and you can apply this phrase for any situation.
One point to note, the Japanese people are known for their punctuality.
If your taxi reservation is for 6.30am, it would be advisable for you to be at the hotel lobby 5 to 10 minutes before your booking time.