A Ticketmaster processing error has caused around 700 people to be charged twice for London 2012 Olympic tickets.
People who bought tickets in the first phase of the 'second chance' sale were affected, according to the BBC. Around 150,000 people in total bought tickets at this stage.
Ticketmaster said that all the people who were overcharged have had their money refunded.
"We are aware of a Ticketmaster processing error affecting a small number of customers who purchased tickets during the London 2012 Olympic Games second chance ticketing process.
This resulted in recent payment for tickets being processed in error twice on 6 July 2011," Ticketmaster said in a statement to the BBC.
"As soon as this issue was identified, a credit was actioned immediately to fully refund the second payment into the same account, which customers will see on their card statements. We would like to offer our apologies for this error and any inconvenience caused."
The London 2012 ticketing system has faced a lot of criticism since it opened.
When the second chance sale opened three weeks ago, users of the London 2012 website faced problems buying tickets due to high demand.
It was then found that problems during the second sale meant that 15,000 people did not get the tickets they thought they had bought.
Meanwhile, in the first round of sales, which started in March, 1.2 million people failed to get any tickets. In addition, the website crashed offline on 26 April after people rushed to buy tickets during the final hours before the deadline.