It's mobile madness and talk isn't cheap!

There are 46 million mobile subscribers in the UK, creating a turnover of a staggering £10.8bn in the last financial year.

No self-respecting child can be without one, whether they need it to send threatening text messages to other children or just to play games on during maths lessons.

And it is the businessman's number one choice for annoying other train passengers or putting other drivers in danger.

Millions of others simply keep a mobile with them for emergencies and use them as little as possible.

However, although they are addictive and handy little beasts, they often disprove the theory that talk is cheap.

Text messages may only cost a few pence, but sending several a day leads to a surprisingly hefty bill.

We sent 13.2 billion text messages between us last year (many of which were surely far from essential).

And, while calling someone on the same phone network as yourself may not be too expensive, calls to people on other networks can hit you painfully in the wallet.

Choosing the right combination of phone, network and payment methods can be a tricky business, whether you intend to use your mobile for just a couple of minutes a day or have your ear permanently glued to your handset.

It's not just a matter of going for a top of the range model or deciding that you can struggle along without being able to send photo messages.

You also need to choose between the options of pay-as-you-go or a contract, as well as picking a tariff that suits the way you use the phone.

New research suggests that many people are getting these crucial decisions horribly wrong.

The Consumers' Association has discovered that 10 million of the UK's adult users could save considerable sums by switching from pay-as-you-go to a monthly contract.

The mobile phone network giants are growing richer with every expensive call, as their customers spend up to £350 a year more than they need to.

Almost half of the 22 million pay-as-you-go customers, those who on average spend £19 or more on calls each month and buy a new handset every 20 months, could be spending more than necessary.

Even people already on contracts could get better deals out of the network companies.

The research by the Consumers' Association magazine Which? found that almost all the 7.8 million contract users could save money by switching to a different tariff.

The average saving for these users has been calculated to be £80 a year, which is not to be sniffed at.

However, 22 million customers have not even considered switching their mobile phone deal and continue to overspend.

Even more worrying is the discovery that 43 per cent of contract customers did not even know what tariff they were on, or could not estimate their monthly bill.

This must all be music to the ears of the four big network companies, T-mobile, Vodafone, Orange and O2.

Which? found that these companies had an unhealthily strong grip on the market, and all had similar price structures to prevent any meaningful competition.

It also discovered that mobile phone shops often give biased information to customers, which is understandable when they are trying to push one particular network.

"There is a fundamental lack of competition in the mobile phone market, which we are calling on regulators to address, but nevertheless, consumers can make significant savings by switching," said Which? editor Helen Parker.

"Our research shows that a small number of savvy customers are already switching to save money, but a huge 10 million could switch and be better off."

The magazine has launched a campaign, "B Mobile", to help the huge number of people languishing in the wrong contract or deal.

It follows earlier campaigns this year, when 350,000 British Gas customers switched suppliers in January and 900,000 customers were helped to escape the clutches of the "big four" banks in May.

It is also helping phone users by setting up a website, www.switchwithwitch.co.uk, where people can compare different tariffs and contracts and see if they can save money.

With Christmas approaching and mobile phones almost definitely featuring on many people's wish lists, a visit to the site before venturing into daunting mobile phone shops could be priceless.

It gives useful and simple information about all aspects of mobile phone deals and could help you to save hundreds of pounds.

By following its independent advice, the millions of customers who are texting and phoning their way into debt could find that Santa arrives early - and ensure that they have a better Christmas than the mega-rich mobile network companies.