The investigation found that the government's introduction of the packs has proved to be an unnecessary cost to vendors, and is not helping the already struggling property market. Both property buyers and sellers are finding it hard to obtain the packs, and the information contained in the packs was often misleading.

Hips have been applicable to all properties since 14 December. The packs include local searches, the property's title deeds and an energy performance certificate, which rates the energy efficiency of the property.

They were introduced with the intention of speeding up the buying process, but a recent survey by the government showed that around 60 per cent of homebuyers didn't believe that the process was made quicker by the introduction of Hips.

Which?'s team of researchers posed as prospective homebuyers in Eastbourne, Ipswich, Leicester and Rotherham. They found proof that some vendors were finding it difficult to obtain the packs, even though they had paid for them.

Two estate agents used the excuse that it was illegal for them to mail a copy, and one seller was asked to pay £20 plus VAT to get a hard copy of the report. When she then asked for an electronic copy, the agent said she would have to come and view it on his office's computer.

The researchers also discovered that the prices vendors were being charged by estate agents varied enormously. In London, the price was £351, but the costs ranged from £234 to £529 in other areas of the country.

Region	Range of quotes (inc VAT)
London	£351 (all six quotes were the same in London)
Oxford/Abingdon	£351 - £529
Rotherham	£347 - £470
Swansea	£234 - £499

The Council of Mortgage Lenders (CML) is also concerned about the length of time the packs are valid for. It believes that the local searches in the packs will be redundant after six months and will then have to be repeated, at extra cost. The Law Society thinks that the searches could expire even sooner.

As well as price, Which?  was also concerned about the quality of some Hips. It asked a Hip assessor to take a look at six packs and he found three to be of good quality, two were average and one was poor.

Which?  spokesman Bob Tolliday said: 'At the moment, it's hard to see how Hips have made the process of selling a house easier and less expensive.

He added: 'If much of the information in a pack goes out of date after four to six months, then that doesn't represent very good value at all.'

The problem with Hips, however, is that it is against the law not to have one when you're selling your property, but there are products on the market which can help you to ease costs.

Sarah Whiteley, a user of Lawpack's Home Information Pack Kit, says ' It helped me to take control of the process and, even better, I didn't have to pay the estate agent to organise the whole thing for me. It helped me to save quite a bit of money.

'It was also easy to give the Hip to the buyer of my house, as everything was on CD.'