2012 ticket sell-off fails to start with a bang

Card fiasco sees thousands blocked from website, while countdown clock grinds to a halt

In an embarrassing case of life imitating art, the Olympic countdown clock broke down yesterday, hours after a TV comedy about the build-up to the Games had depicted a similar debacle.

Organisers were also forced to defend the ticketing system after people whose Visa cards will expire before the end of August found that the website refused to process their orders. London 2012 said that although the application process started yesterday, cards must be valid in May when payment is taken.

Visa apologised, adding: "We are working closely with all relevant parties to resolve this issue as soon as possible." The digital clock in Trafalgar Square was started in a whirl of flashing lights and fireworks on Monday night by the chairman of the Games organising committee, Lord Coe, to mark 500 days until the Games begin.

That night, the BBC aired Twenty Twelve, a satire imagining the bureaucratic balls-ups behind closed doors at the Olympics. In the first episode, the team unveiled a giant alarm clock outside the Tate Modern, but the timepiece began its countdown on the wrong date.

Despite the modern design of the real clock, made by Omega, it ground to a halt after less than 18 hours – 500 days, seven hours, six minutes and 56 seconds before the start of the Games.

A spokesperson for Omega said: "We are obviously very disappointed that the clock has suffered this technical issue. The Omega London 2012 countdown clock was developed by our experts and fully tested ahead of the launch in Trafalgar Square."

Six hours after the company's engineers arrived to fix it last night, the clock was back up and running, having been adjusted to compensate for the mishap.

Speaking in character as Ian Fletcher, fictional head of the Olympic Deliverance Commission in Twenty Twelve, one of its stars, Hugh Bonneville, offered a perfect politician's response: "It hasn't stopped. It's a powerful and, at the same time, playful comment on the way in which time itself seems to stand still when you're talking about something as exciting as the Olympics. So basically, it's all good." The clock, which is 21ft high, 16ft long and weighs four tonnes, took 10 people two days to assemble.