Carillion is suing the client, developer Birmingham Mailbox, for more than £5m.
The dispute has left two of the three main parts of the development – the 180-room hotel and offices for BBC Midlands – incomplete, say sources close to client Mailbox. The public square, including shops and restaurants, is finished.
A source said that work due to be handed over between June and October of last year was still awaiting completion.
The dispute originates in a payment claim submitted by Carillion on 1 December 2000.
The claim, for construction, alteration and extension works on the site, a former post office building, was for £38.25m, £11.5m above the original contract value of £26.755m.
When Birmingham Mailbox responded with a payment of £1.4m, believed to be the usual monthly amount, Carillion issued an invoice for an interim payment of £5.27m. The firm claimed that the value of the contract had gone up because of adjusted costs.
The case was due to be heard yesterday by Judge Richard Seymour at the Technology and Construction Court. Carillion said it would be inappropriate to comment until after the hearing. Birmingham Mailbox also declined to comment.
The Mailbox claims to be Britain's largest mixed-use building and is considered to be central to the city's massive regeneration boom.
A residential scheme by Crosby Homes makes up the top level of the project, which is the brainchild of property consultants Alan Chatham and Mark Billingham. Both previously worked on the nearby Brindleyplace district, also the subject of major regeneration work. Other regeneration schemes nearby include the £800m redevelopment of the notorious Bull Ring and the Nicholas Grimshaw & Partners £110m Millennium Point science and technology centre.