Our guide to protecting your pocket from pricing scams

Over the past six weeks we have highlighted six retail areas blighted by hidden charges. This is what we found, and this is what you can do about them:

Holidays

UK travel companies are adding hidden extras to flight and holiday prices, in direct contravention of the rules on advertising. We found a holiday which the company offering it said cost as little as £39 but which actually cost £105. Phil Evans, principal policy adviser at the Consumers' Association, advises avoiding package holidays altogether. "Unbundle it yourself. Do your own research and you can often book it cheaper. IoS readers are internet savvy, and the vast majority of holidays you can organise yourself."

Car rental

Transaction fees, insurance waivers, credit card charges, an array of surprise penalties. Car rental is a byword for hidden charges that can catch out even the most astute customer. One IoS reader reported that he was charged £20 simply for the pleasure of picking the car up. "There's a hell of a lot of small print with car rental," says Mr Evans. "So, try to examine it in advance when you have time. Avoid disputes over the condition of the car when you return it by photographing the vehicle to prove that you have not put any dents in it. Sean O'Grady, motoring editor of The Independent, says that arguing the price at the end of the transaction has always resulted in a reduction.

Banks

Banks have a knack of imposing an array of hidden charges. This often creates further problems: punitive fees for an accidental overdraft can add up to £80 a month. When choosing a financial product check when penalties start kicking in. Shop around for the best rates and lowest charges, using a website such as moneysupermarket.com. If you are taking out a personal loan, opt for one that doesn't charge a penalty if you repay the money early. And with mortgages, ask for your money back if a lender charges a penalty for not buying their buildings insurance.

Mobile phones

Mobile phone companies benefit from the complexity surrounding the myriad deals and tariffs available. Mr Evans's first rule is: do your research before you sign up for a mobile. "Don't be lured by some offer of 2p a minute. And don't walk in to a store and expect impartial advice. Get your information in advance. Look at brochures, and check websites. Also think about how you are going to use your phone. If it's to keep in touch with a small number of people, try and be on the same network. Don't be dazzled by functions you are not going to use." Beware also of the cost of using your mobile abroad.

Theatre booking fees

Booking agencies say they are providing a "service" and need to recoup their costs. But even booking over the internet - ie, doing all the work yourself - provided no escape from this hidden charge. One way of avoiding paying more than the face value of the ticket is to book it in person. But some shows have no in-person booking facility. There's no such thing as shopping around. If there's a show you want to see, then that's the show you'll book for. "We feel this is one for the regulators," says Mr Evans. "The Office of Fair Trading needs to look at this." Complain to the OFT and complain to your MP, Mr Evans adds. "Objections from the public can only help."

Restaurants

We highlighted a scam perpetrated by many restaurants - the practice of including a 10 or 12.5 per cent service charge on your bill and then inviting you to fill in an empty "gratuity" box on your credit card slip. "A complete no-no," says Mr Evans. This still doesn't address the problem of service that is included. Remember: you don't have to pay it. If you think the service wasn't up to scratch, you definitely shouldn't. "Subtract it from the total," says Mr Evans.