Credit card companies are "adding insult to injury" by keeping people in the dark over why their applications have been rejected, consumer campaigners have found.
Which? said firms are leaving consumers confused by failing to give enough constructive advice about why they have been turned down.
Nearly half (48%) of people surveyed by Which? who have had an application turned down in the last two years were dissatisfied with the level of information given over the reasons for refusal.
The most common gripes were to do with poor communication and not enough evidence about why the application was rejected.
Eight in 10 (79%) said they were not given specific reasons for the rejection, with three in 10 (30%) saying they were not given any reason at all. Half (49%) said they were just told to check their credit file. Lenders must tell consumers if they are rejected based on information from a credit reference agency, and provide details of the agency.
Which? executive director Richard Lloyd said: "Credit card providers are letting people down by failing to give them constructive advice after a rejection. We want lenders to give a useful reason for a refusal and practical tips so borrowers can take steps to improve their chances of being accepted in the future."
Mr Lloyd said people should be able to shop around more easily without being penalised. He urged all companies to use quotation searches so that consumers can see whether they might be accepted without a full application "footprint" being recorded on their credit file.
Some comparison sites and lenders already offer a quotation, which allows lenders to give a quote based on a borrower's circumstances and indicate how likely it is that they would be accepted. This allows people to shop around for credit without it showing on their credit file.
If someone is turned down for credit, reapplying straight away could result in more rejections as too many applications in a short period may make lenders reluctant to lend.
More than 2,000 people took part in the research.