Uber boss Travis Kalanick has apologised after a video emerged of him swearing at one of the company's drivers.
The outburst came after Fawzi Kamel, who was driving the chief executive, complained his income was falling and blamed Uber's fare structure.
In an email to staff, Mr Kalanick said he was "ashamed" of his behaviour and admitted he needed to "grow up".
Just two weeks ago he apologised for "abhorrent" sexism at Uber.
And on Monday, Mr Kalanick asked his engineering chief Amit Singhal to resign following a related development.
Bloomberg published the video showing a row between Mr Kalanick and Mr Kamel, a driver who picked him up in early February.
After a back and forth about lower prices on Uber's service, Mr Kalanick eventually told the 37-year-old: "Some people don't like to take responsibility... They blame everything in their life on somebody else. Good luck!"
During the argument, he swore once at the driver.
In his staff memo, Mr Kalanick said: "By now I'm sure you've seen the video where I treated an Uber driver disrespectfully, To say that I am ashamed is an extreme understatement.
"My job as your leader is to lead… and that starts with behaving in a way that makes us all proud. That is not what I did, and it cannot be explained away.
"It's clear this video is a reflection of me - and the criticism we've received is a stark reminder that I must fundamentally change as a leader and grow up. This is the first time I've been willing to admit that I need leadership help and I intend to get it.
"I want to profoundly apologise to Fawzi, as well as the driver and rider community, and to the Uber team."