Delivery guys cancelling pick up

Placed an order at 7pm. Food was ready around 7:30 but the delivery guys kept on cancelling delivery because I paid online. Two hours later, there was still no delivery guy willing to deliver my food. My house is just 5 km from the restaurant. Why do drivers accept pick up and thereafter cancel? How are you going to address this issue? Is there any consequence Management to follow against these drivers? Whose fault is it that they are not taking this delivery. I have been a valued customer of Uber for years and now this. This is really disappointing