Users of mobile phones waste £5 billion ($8 billion) a year by being on the wrong tariff, says a new study, with some £173 million ($275 million) coming via additional data charges from roaming the internet.

Carphone Warehouse surveyed 2,034 people, and discovered that almost half (47 percent) were unaware of the data allowance or free minutes and texts on their contract, leading them to overspend by an average of £194 per person per year. The rapid adoption of smartphones has exponentially fueled the sharp rise in mobile data usage, with a large percentage of that coming from social apps such as Twitter and Facebook.

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