Roaming charges are back with a bang since Brexit, so if your mobile is never far from your hand it is important to make sure your post-holiday glow isn’t ruined by a shock bill for calls and data when you get home.

Almost all the big mobile phone companies, including EE, Sky Mobile, Three and Vodafone have reintroduced EU roaming charges, with giffgaff and Tesco Mobile the latest names to announce contract changes.

Giffgaff has told its customers that from 26 July they can only use up to 5GB of data a month in the EU. Above that level they will be charged 10p a MB. In a post on its website, the company blamed the move on the connection charges incurred when people roam in the EU.

Giffgaff said it had “taken the decision to mitigate some of that cost, so that we can at least give our members up to 5GB to roam in the EU, at no extra cost”. It pointed to 2019 usage data, which showed more than 90% of its members had used less than that figure when roaming in the EU.

In another change, the sun is setting on the free roaming enjoyed by Tesco Mobile customers on its Home from Home contract. From the start of 2023, new sign-ups and upgrade customers will lose this benefit; existing customers will continue to enjoy this perk provided they don’t change their device or move to a sim-only contract. The roaming charges will be 10p a MB of data, 20p a text and 55p a minute for calls.

In 2017, mobile networks in EU countries were banned from charging customers extra to use their phones in other member countries, with the right to make calls, send texts and, most importantly, use data allowances anywhere in Europe – as if at home – one of the most popular pieces of European legislation in the UK. However, the Brexit deal did not include continued protection against roaming charges.

With charges differing across the networks it is a “confusing time” to travel with your phone, says Ernest Doku, a telecoms expert at the price comparison and switching service Uswitch.com.

As a first step, Doku suggests you check the roaming charges for your destination and see if your provider has a fair usage policy. This means they can restrict your full UK allowance even if you are on an unlimited plan at home. Three, for example, has a fair usage limit of 12GB, and you will be charged £3 a GB if you exceed it.

Of the big four firms, O2 is the only one that says it is not currently planning to bring back roaming fees, while Virgin Mobile customers should also be safe from roaming charges “for this year at least”, Doku says.

“Depending on when you last took out a mobile or sim deal, or upgraded your phone, you may be shielded from your provider’s new roaming charges as they will not have been written in your contract at the time,” he adds.

If you change networks you may be able to keep roaming at no additional cost – and also save money on your bills. “O2 is the last major network not to bring back roaming fees for customers travelling to the EU but some smaller sim-only networks also offer inclusive roaming in Europe and could be a good option if you are not venturing too far afield,” Doku says.

The easiest way to avoid accidental charges while abroad is to go into the settings menu of your mobile and turn roaming off. If you need to get online, use the wifi in your hotel or in local restaurants and bars. Also remember to put your phone in flight mode when you are in transit to avoid incurring charges as you pass through different territories.

Another radical option is to switch your phone off and just relax. Go on, you know you can do it.