Some Apple iPhone users have received hefty bills after foreign trips, despite switching off data-roaming.

Using the internet, email or, indeed, any application that downloads data, can be a very expensive business for smartphone users when they travel abroad. Foreign network providers will charge a huge amount for using their data. As a consequence, iPhone users are urged to disable data-roaming whenever they travel - a simple process designed to stop them incurring such high bills.

But some iPhone users who had turned off data roaming have complained to the moneysavingexpert.com that they have still been hit by bills. In the worst case, reported in The Telegraph, one user claims to have been charged almost £1,500 after a trip to the US.

According to The Telegraph users who have complained to their network have been given refunds. All major networks have been affected.

Martin Lewis, founder of MoneySavingExpert.com, said: "Those who have paid when they shouldn't have, should contact their network immediately and demand a refund. In some cases, we're hearing the networks are paying out without too much argument, which could indicate this is a known problem. Let's hope it does not get brushed under the carpet."

As well as the usual precautions, iPhone users are being warned to ensure that their phone software is up to date. Because legislation now caps the amound that can be charged for data-roaming within the EU, the complaints have almost all originated from journey's outside of Europe.

To find out how avoid such charges, read: Taking the iPhone abroad? Here's how to avoid data-roaming charges.

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