New rules that will cap mobile roaming fees across the EU are introduced on 1 July, but research shows that one in six holidaymakers still suffers from "bill shock".
The roaming charge cap will lower costs for consumers travelling within the EU, taking the maximum charge for downloading data from 45 cents to 20 cents (around 16p) a megabyte; outgoing calls drop from 24 cents to 19 cents a minute; outgoing texts fall from 8 cents to 6 cents a text; and incoming voice calls now cost 5 cents instead of 7 cents a minute.
Neelie Kroes, vice president of the European Commission responsible for the Digital Agenda, said: "This huge drop in data roaming prices will make a big difference to all of us this summer. But it is not enough. Why should we have roaming charges at all in a single market?
"By the end of this year I hope we see the complete end of roaming charges agreed - the Parliament has done their part, now it is up to Member States to seal the deal."
The new caps only apply to mobile use within the nations of the European Union, meaning holidaymakers who travel further afield still face the prospect of a huge bill.
Research conducted by consumer rights group Which? indicates that nearly one in six people have experienced a bill shock. It found that 17% of people who have taken their mobile on holiday abroad in the last year have been shocked by a high mobile phone bill. Of these, one in four (25%) were charged more than £40 over their usual monthly usage.
Which? executive director, Richard Lloyd, said: "Capping EU mobile roaming charges is welcome news for millions of travellers, especially those who have faced expensive charges for data roaming when their mobile hasn’t even left their suitcase."
"Consumers travelling within the EU should now be much clearer on the charges they have to pay."
Roaming charges were at their peak around 7-8 years ago, with the EU finally starting to take action in 2007. Roaming fees subsequently fell, by about 80-90% between 2007 and 2014.