More than 17,000 Digital Covid Certificates had to be re-issued in recent days because of a missing síneadh fada in people's names, Tánaiste Leo Vardakar has confirmed.
Conradh na Gaeilge had complained about a number of misspellings of names in Irish on some of the more than 2 million certificates issued over the past week.
Mr Varadkar said the mistakes in relation to the fada had been rectified.
He said that part of the problem with delays in the Digital Covid Certificate Helpline number is that people are ringing in with all sorts of queries not related to the cert, including questions about indoor dining in other countries.
Mr Varadkar said the helpline is there to apply for a Recovery Certificate for those who have had Covid-19 and for problems with digital certificates for those who were vaccinated.
Under 7% of 70,000 calls dealt with in first three days
The Digital Covid Helpline was only able to deal with under 7% of the 70,000 calls received in the first three days.
The Department of Health has again asked that only those travelling in the next 10 days should call.
"Current demand suggests that many people are calling that are not due to travel in the short term. These non-urgent calls are adding very significant wait times to all calls, and preventing many urgent calls from getting through," it stated.
The volume of calls has far exceeded what was expected following assessment of travel bookings but the issuing of over two million certificates in just over one week has inevitably "bunched" inquiries to the centre, the statement added.
The Department also said the queries are complex with over 150 scripts developed to assist agents and many are multiple requests from a family.
There are currently 80 agents operating the lines and a total of 4,761 queries were dealt with in the first three days.
Meanwhile, one man told RTÉ News that he is on his fourth day of trying to get through to the helpline and has been left on hold for hours at a time during 11 different attempted calls.
He said he was once waiting for two hours when the call went dead.
The man, who is on disability benefit, was fully vaccinated, but did not receive a digital cert and is travelling to Europe for keyhole surgery within a week.
He said his local TD told him to bring his vaccination card to the airport and borrow money to get a PCR test.