What helps an urgent request
For an urgent requirement, the quickest way to get a response is a complete request: the pickup address, when you need the driver to arrive, the destination and a phone number you will answer.
Say what has gone wrong, for example your regular driver is unavailable or a family situation has come up. This helps the team judge priority, although a suitable driver cannot be promised for a fixed time.
Keep your phone reachable after you send the request, because the team may need to confirm the details with you before assigning a driver.