Driver shortages and IT problems have been blamed for "phantom" or "disappearing" buses in Dublin and Wicklow.
The two main bus operators in the capital have appeared before politicians to explain recent issues with services.
Commuters in Dublin and North Wicklow have been complaining of increasing problems with real-time passenger information and so called "phantom" buses leaving commuters stranded at stops.
Dublin Bus says it's been working hard to fix software problems that have coincided with serious driver shortages.
The company says its resulted in some trips being cancelled, which should removed from the real-time system but in some cases it says this wasn't happening.
A new process is being put in place to address the problem.
Dublin Bus says despite hiring an extra 290 drivers this year, it's not keeping pace with the rate the network is expanding.
Go Ahead says its also been hit with staff shortages - that's been hampered by a backlog in getting essential paperwork for new drivers.
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