An urgent report has been ordered into the company behind a cashless parking app after customers were issued tickets and overcharged.
A breakdown from the Department of Infrastructure shows 23 people were fined and 169 customers incorrectly billed by JustPark since it launched four weeks ago.
Alliance MLA Andrew Muir requested the figures after he heard from a JustPark customer who got billed £90 - and a £90 parking fine.
The department changed cashless parking provider on January 6.
There have also been 85,000 "successful transactions" since the switch.
But Mr Muir said the error rate was "very concerning". He was also contacted by a customer who got back to her car just as an officer was writing up a ticket.
Mr Muir said: "When you’re trying to move people onto cashless payments, problems like this don't give people much confidence."
Responding to Mr Muir's questions, Nichola Mallon said her department "would not tolerate further errors".
All fines have been overturned, and JustPark said it had credited overcharged customers.
Ms Mallon said: "While I understand that initial teething problems can and do occur when new contracts take effect ... I have asked for a full and urgent report from the company".
She said JustPark had apologised to customers.
JustPark has been contacted for comment.
