According to uSwitch.com, nearly one in ten (9%) pay monthly customers overpay by £25 every month, while more than one in four (27%) overspend by at least £10 a month.

The main reason for overpaying is making premium rate calls, with one in four being burnt, while over a fifth (21%) blame roaming charges abroad and forking out for competition voting lines and texts leaves 12% as losers in the bill stakes.

Worryingly, more than one in ten (12%) British adults are totally in the dark, having absolutely no idea where their money is going.

Consumers are also blindly racking up bills because they do not sort out their finances themselves – 14% rely on partners and housemates to take care of their mobile, broadband home phone or TV bills for them. Of those who don’t handle their own bills, almost a quarter (23%) have never thought to check what they are paying, or asked the bill payer to look into getting a better deal by switching providers.

Brits are also slack when it comes to checking usage with almost a fifth (18%) never receiving itemised bills.

Ernest Doku, telecoms expert at uSwitch.com, said: “Budget-conscious Brits are signing up to pay monthly mobile deals with the promise of plenty of calls and a set monthly bill. However, while it’s all well and good having a mobile bundle with stacks of minutes, texts and data, calling premium rate numbers, voting by text for your favourite music acts and incurring roaming costs when abroad can render them useless, as these are often not included in your tariff.

“The problem isn’t necessarily a cavalier or complacent attitude to these charges, but the fact that people just aren’t aware of how much they are going to cost. Simply being aware of out-of-tariff charges can save pounds each month and itemised bills are a great way of monitoring usage, and keeping tabs on whether the deal you have is right for you.

“If someone else looks after the bills, lucky you – few enjoy extra paperwork. But if you are paying then it’s in your interest to see if you could get a cheaper deal by moving elsewhere.

“For those savvy consumers who know when their packages are up for renewal and shop around, there are some great deals to be had. If your bills are too high, burying your head in the sand won’t help. If you’re switched on to your bills – how much you’re paying and precisely what you’re using – you can make sure you’re on the best plan for you, saving money in the process.”