The trouble this week f' />

Auckland's Northern Gateway toll road has struck another technical problem, overcharging about 2000 motorists by $45,000.

The trouble this week follows refunds of about $200,000 to 424 motorists last week after their prepaid toll accounts were overcharged by an average of 23 times each.

Agency motor registry manager Brett Dooley was particularly disappointed by the recurrence of a computer server problem after an assurance by the Swedish supplier of world-leading electronic toll collection technology that it had been fixed last week.

Mr Dooley said the latest batch of motorists were being fully refunded, but he had ordered a shutdown of an account top-up facility on the toll road's website until he could be sure the problem had been rectified.

That was because duplicate charging occurred when toll accounts were being automatically topped up against customers' credit cards, after dipping below a minimum level of $10.

He hoped for progress in a conference call with the supplier's software developers in Argentina this morning.

The new road is proving popular with motorists, but the toll collection system has been plagued by problems.

Even before the road opened in January, the Transport Agency had to shut the account section of its website for a week until it was able to safeguard credit card details, which were being sent across the internet unencrypted.

And although overhead gantries are supposed to photograph the front and rear number plates of every vehicle passing below, a Herald reporter who has yet to receive a bill for using the road more than a month ago has been told by the agency's call centre that it has no record of his trip.