When the Uber he'd hired went to the wrong destination, one professor took his complaint to the very top - and then learned something valuable about the science of apologising.

In January 2017, John List was due to give a keynote speech at a prestigious gathering of economists. He picked up his phone and, using the Uber app, booked a cab to take him the 30-minute journey from his home. He looked up briefly, as the car sped along Lake Shore Drive, on the banks of Lake Michigan, and took in the view of the approaching city, with its fabulous skyline of skyscrapers. Then he settled back down to work on his talk.

About 20 minutes later he looked up again. Surely he must be nearly there now? "Oh no!!" he screamed. He was back where he'd begun. Something had gone wrong with the Uber app, which had instructed the driver to return to the professor's home. She had not wanted to disturb him, as he was so engrossed in his work. slotxo

List was understandably furious. But what made him more so, was that Uber never sent him an apology.

Not everyone who has a complaint to make with Uber has access to its chief executive, but John List did, and so he rang Travis Kalanick that evening. (This was not long before Kalanick was forced to step down as a result of shareholder pressure, following a series of controversies over company practices including its handling of sexual harassment allegations.)

After List had related the tale, and let off a bit of steam, Kalanick spoke. "What I want to know," he said, "is how Uber should apologise when this sort of cock-up occurs. What's the best way to keep Uber customers loyal, even when they've had a miserable experience?"

How to apologise is a question which every company is interested to know the answer. And John List was in a unique position to find out.