Accenture has lost a preliminary appeal to block a £182 million lawsuit by British Gas following problems with a billing system that it implemented in 2006.

In a judgement handed down on 30 July, three High Court judges upheld nine out of 10 claims by British Gas that were initially ruled on by the court in November. This means that the case will now be heard in October next year.

The utility is suing Accenture for damages, after claiming that the Jupiter billing system it introduced was "inadequate", led to "millions of errors" and caused "huge disruption" to both the company and its customers. As a result, service was affected, clients had to make lengthy calls to try and rectify problems and the firm lost customers, it attests.

But Accenture has denied the claims, saying that the applications met all of their contractual requirements and were delivered on time and to budget. It also attests that British Gas approved the system after extensive testing and only brought the lawsuit two years later as a result of "mismanaging" it.

The consultancy likewise argued that there were deliberate exceptions built into the system for bills that needed to be reviewed manually and that these were not errors.

In a situation that could make it more difficult for British Gas to blame Accenture for any errors and hold it liable for fixing them, however, the judges upheld the consultancy’s argument that there was an important difference between system defects that actually led to problems and those that "could cause" them.

But Phil Bentley, British Gas’ managing director, told tech magazine CIO that the company was now "one step closer to holding Accenture to account for the disruption caused to our customers".

Accenture, on the other hand, said: "What British Gas didn’t mention in their statement is that the Court of Appeal in fact accepted a number of Accenture’s arguments."