Five separate complaints involving Eir's advertisements have been upheld by the advertising watchdog.
The complaints centred on misleading information around promotions for mobile plans and broadband coverage.
In total, 18 advertisements were found to be in breach of advertising standards according to the Advertising Standards Authority's latest report.
A single promotion by Bia Belle Beauty on mink lashes also attracted four complaints, with people claiming it was not possible that hair obtained from a caged mink could be "cruelty-free."
Other companies which were found to have misleading information is their advertisements were AIB, Ben Dunne Gym, Nature and Harmony, ieDepot, Therapie Clinic, Volkswagen Bank, Sherborough Enterprises, Andrew Beatty Fitness and UK Direct Shop.
A complaint over a promotion on social media by Showtime Essential Kitchen Products was also upheld.
Complaints against Smovey Health and MyRefund.ie by interested parties or those in a similar industry were upheld by the ASAI.
One complaint against Diageo over an ad featuring young people at the beach and drinking alcohol was not upheld.
Commenting on the latest ASAI rulings, Orla Twomey, Chief Executive of the ASAI, said: “The latest complaints bulletin from the ASAI illustrates our ability to handle complaints across a large number of mediums.
Professor Bairbre Redmond, Independent Head of the Complaints Committee of the ASAI, said: “Over the past few years, the Complaints Committee, comprised of independent and industry members, has dealt with a broad range of complaints.
"The Complaints Committee has also spent considerable time highlighting awareness in relation to advertising best practice within the advertising industry, ensuring all relevant parties are equipped with the knowledge and resources to correctly identify commercial marketing content across their platforms.”