Lobby group IrelandOffline has raised concerns over Eircom's decision to move from a speed-based to usage-based price model.
The group has explained that the ISP's subscribers now face a 2 (£1.80) charge for every gigabyte they go over their monthly usage limit.
IrelandOffline claimed that "all but the lightest users" will run up monthly bills of up to 50 (£45), as the usage caps are "paltry" in relation to modern user demands.
"For instance the Broadband Basic package has a minuscule 10GB cap, barely enough for the average tech-savvy family," the group stated.
"This is yet another attack on the hard pressed telecommunications consumers of Ireland."
IrelandOffline Chairman Eamonn Wallace recently criticised the broadband speeds accessible to Irish consumers, after Akamai reported that the nation has the highest percentage of slow connections in Europe.