The singer, who had an unhappy 19th birthday in the British capital on Friday, was forced to apologize to angry fans after he was almost two hours late taking the stage Monday night at the O2 Arena.
The show was scheduled for 8:30 p.m., but the pop star didn't walk out until almost 10:30 p.m., according to the BBC.
"My daughter was very disappointed as he played a much shorter set and there was obviously an awful lot of songs missing. I think he was on stage for only an hour," one mom told the BBC of their experience.
Bieber apologized Tuesday on Twitter, but insists he wasn't as late as people said.
"last night i was scheduled after 3 opening acts to go on stage at 935 not 830 but because of some technical issues i got on at 10:10," he writes. "i was 40 min late to stage. there is no excuse for that and I apologize for anyone we upset. However it was great show and Im proud of that."
He added: "i never have any intent to upset or let anyone down. and Im not okay with things being exaggerated. once again sorry for anyone upset. now we have a show to do today and Im gonna focus on the positive and put on a great show tonight here in London."
The BBC caught up with more fans outside the arena and one told them, "They were playing Michael Jackson song, after song, after song – it was so annoying ... as more time passed, everyone was getting more worried and booing."
Monday's concert was the first of four nights the singer is booked at the O2 Arena, which Tweeted Tuesday morning that it will be "exploring all available options to ensure this doesn't happen again" and posted the next start time for Bieber.
We have been informed by the @justinbieber team that he is scheduled to go on stage at 9pm tonight. Support acts start from 7pm. Thank you— The O2 (@The_O2) March 5, 2013