More than 67,000 people have been billed incorrectly since Barrier Free Tolling began on the M50 in August last year.
Figures obtained by RTÉ News show that the system has been misreading 200 cars a day.
They also show that 12,500 people a day are not paying their toll within the required time.
However, the operators say the system is improving.
Barrier Free Tolling on the M50 began last August, with it came freer flowing traffic but it also resulted in a barrage of complaints.
Figures obtained by RTÉ under the Freedom of Information Act shed some light on the source of the problems.
The system has been misreading 200 cars a day.
That has resulted in more than 67,000 people being issued with incorrect notices to date.
But the system has also been unable to read about 160 cars every day, so over 54,000 motorists have literally gone under the radar.
Around 12,500 journeys a day are not being paid for within the required time.
4,000 notices are being issued daily to those who have not paid within 14 days.
2,500 people a day are failing to pay up by the final deadline of eight weeks resulting in penalty proceedings being issued.
However, BetEire Flow who operate the system say it is improving and that the number of complaints and problems are declining.
5,000 legal proceedings have been initiated to date - all that went to court were won by the NRA.
The call centre operator has been changed because of complaints.
They are getting 34,000 calls a week, but they are now generally being answered within 30 seconds.
Some people have complained of being sent notices when they were not even on the M50 ,but the NRA says 70% of these claims were found to be invalid.
The operators say there is an element of people taking a chance by not paying their toll.
But they say improved technologies and systems should discourage that in future.
