It found that one in seven new mobiles had problems, 70% of which occurred in the first six months.

Twenty-seven percent of mobile owners with problems were not happy with the help they received either, said Which?

Video phone operator 3 had the poorest record, with one in three handsets on its network having problems.

Which? said that this could be down to "teething problems" with third generation mobile technology.

"They're newer and they are more sophisticated so it is reasonable to think they might have more teething problems," Abigail Waraker, assistant editor of Which? told the BBC News website.

Rachel Channing from 3 told the BBC News website that it was unrealistic to try and compare 3G technology, which is complex and new, to GSM technology.

Downloading full-length music videos, making video calls and so on is relatively novel for many people, so there was more chance of things going wrong.

She also criticised the sample size of the survey.

"The sample they picked out was only 50 customers. We have three million. It was only 16 who had experienced problems, so we don't think it is a representative sample," she said.

She added that the problems reported related to its oldest 3G handset model, released about two years ago.

"The technology is evolving so rapidly and the performance as you release them improves every time.

"Those handsets have been superseded by ones that perform much better on the network," she said.

The survey revealed a whole range of problems, from faulty keypads, failure to connect to the network, or problems in storing phone book entries, for instance.

By law, if a mobile has a fault within six months and the store cannot show it was the customer's fault, the shop must sort it out.

'Not good enough'
The report did not make distinctions between what was a handset fault, or a network fault because people would not necessarily know themselves the reason for a fault.

What it highlighted though was a big problem that new mobile owners experience when there is an issue.

"People get passed from pillar to post," Pete Tynan, the report's author told the BBC News website.

"In fact is it is up to the place you bought it from to sort it out. Don't let them fob you off," he said.

Even if the problem was that the SIM card was not connecting to the network, for instance, it is still legally the retailer's responsibility to solve the problem as they sold the package in the first instance.

"A one-in-seven chance your phone's going to develop a fault is way too high," said Malcolm Coles, editor of Which?.

"Not only that, but retailers who should be bending over backwards to help customers who've already suffered the inconvenience of a fault, aren't giving people the help they need when they complain."

The survey of more than 5,000 people on Which?'s online consumer panel also found that certain handset brands were more likely to experience faults than others.

Motorola and Sony Ericsson handsets proved most likely to have technical hitches, with 20% of people reporting problems with them.

Nokia and Samsung scored better, with one in 10 owners experiencing faults.

Mobiles are fast becoming the most common consumer electronic devices in the world, according to analysts.

By the end of 2009, 2.6 billion mobiles will be in use around the world, according to Gartner analysts.

From BBC News