The temporary software patches used to plug the gaps left by the catastrophic failure of their £335,000 Liquid Box Office system were unable to cope with the half-price sales.

Frustrated festival goers had to make their way on foot to the Half-Price Hut to take advantage of the final day's deals, despite initial promises in the brochure that tickets would be reduced "at all Fringe ticket outlets".

Mailing list customers were sent a last-minute e-mail at the weekend informing them that the box office was unable to proceed with the Fringe Ticket Frenzy, but that they could still "treat" themselves to a ticket bargain by heading down to the hut.

Customers had to wait around half-an-hour as long queues formed at the Princes Mall outlet yesterday.

Among them was solicitor Robert Finney, 53, who originally hails from Morningside but now lives in London.

Mr Finney had tried to book tickets for Under Milk Wood at the Shed Theatre over the phone yesterday morning.

He said: "They couldn't even tell me whether the show existed, let alone whether the tickets were half-price or not.

"They said the only way I'd be able to find out was to go to the venue. But, as the only place selling half-price tickets is the Princes Mall ticket hut, I would have had to get to the location, find out if it was on and come back to the ticket tent to buy the tickets, by which time the show would have finished.

"There just seemed to be a basic lack of communication. Junior staff were telling me that their supervisors were the only ones who had the information on what tickets were half-price, but that there was no-one around to help me."

Mr Finney was forced to head down to Half-Price Ticket Hut and found his preferred showing was not on the list, so he purchased two half-price tickets for Othello at the Hudson Hotel.

The company that designed the failed Liquid Box Office system, Pivotal Integration Ltd, has now gone into administration and the Fringe has to decide whether to proceed with an amended version of the software and seek independent support, or scrap the whole project and start again with something new.

The Fringe is also facing a massive bill from venue managers who have been forced to hire extra staff to cope with the difficulties.

Festival director Jon Morgan, who has already admitted that his own job may be on the line as part of an independent review into this year's ticketing debacle, apologised for the ongoing problems.

He said: "We were planning to make half-price tickets available across all Fringe box office outlets, but unfortunately this was not possible because we are running two different ticketing systems this year."