Three popular screens have failed an independent protection test and could not provided the protection from damaging UV rays they claimed to offer, a consumer watchdog found.
Which? tested Piz Buin Ultra Light Dry Touch Sun Fluid SPF30 150ml, Malibu Protective Lotion SPF30 200ml and Hawaiian Tropic Satin Protection Ultra Radiance Sun Lotion SPF30 200ml, which all claimed to be SPF 30.
They all had lower results than SPF 25.
The consumer group has branded the creams as "don't buys" in its investigation, which used British Standard tests to check 15 products with an SPF (sun protection factor) of 30 - a bestseller in the UK.
A third of people who used a public service in the last year and were dissatisfied with it did not complain, with the most common reason being "it would not be worth the effort", according to a Which? survey.
In response to a Which? study that concluded it is "virtually impossible" for people to calculate and compare current account costs, the Government said it is "clear" that customers must have easy access to clear information on overdraft charges.
It confirmed that a "more robust regulatory system" will be in place soon.
Through the midata initiative the Government is encouraging banks to give consumers information about their spending patterns so they are able to find the best deal for them.
They already have access to free text alerts when a balance falls below a certain level, a free seven day current account switching service, while a more robust regulatory system that will help deliver for consumers will be in place soon.
Current account providers are using vague language and baffling charges structures making it very difficult to calculate the cost of slipping into an unauthorised overdraft, research from consumer watchdog Which? has found.
The consumer group used 18 volunteers, including a principal inspector of taxes and a retired headteacher, to work out what the cost of an impromptu overdraft would be using a mock statement and charging structures on the bank's website.
The volunteers got just 10 out of 72 calculations correct between them, with the tax inspector getting just one of his four calculations right and the former headteacher getting them all wrong.
Richard Lloyd, executive director of consumer rights organisation Which?, said the reforms were a step in the right direction but did not go far enough:
This is why the Government should intervene with more radical measures including simpler pricing, greater transparency and scrutiny of the cost of energy policies, and the separation of domestic supply from generation businesses.
More must be done to keep prices in check and give consumers confidence that the price they pay for their energy is fair.
Consumer watchdog Which? has called on leading financial providers to follow the example of a minority of firms that have dropped costly call numbers.
Barclays and Barclaycard said they will now offer a freephone or basic rate number for all customer help lines.
We applaud Barclays and Barclaycard for breaking from the pack on high rate numbers and want to see other financial firms follow their lead.
It's great news that NatWest and RBS are doing the right thing for their customers by dropping costly calls. The new leaders at RBS have promised to renew the banks' efforts to improve customer service and this is a very welcome start.
With two of the biggest banking groups now leading the way by offering freephone or geographic numbers, we hope this is a tipping point for the banking sector - there's really no excuse for other providers not to follow suit.
Consumer watchdog Which? found 95% of credit card providers studied and 89% of current account providers use expensive 084 or 087 numbers for complaints or customer service help lines.
Existing customers are also being charged more than new ones, with free 0800 numbers used for 52% of sales or new customer lines compared with just 26% for existing customers and 21% for complaints.
The survey of 2,070 found 39% prefer to call financial firms with an inquiry and 31% would rather complain by phone.
A British Bankers' Association spokesman said:
All banks are actively looking at how they can reduce costs for customers. We expect to see many banks changing to use local numbers for complaints in the near future and it is good to see that some banks have already committed to doing so.