In the second programme of the series, Inside Money looks at a controversial type of insurance which critics argue can let consumers down badly when they need it most.
Critical illness policies are designed to pay out a tax-free lump sum if the policyholder develops certain life-threatening illnesses like cancer, a heart attack or stroke.
Many people take them out for peace of mind when they sign up for a mortgage.
But around 20% of claims are rejected. Of this 20%, around half are rejected for "non-disclosure", which is where an insurer finds out that a pre-existing condition has not been brought to their attention.
The other half are rejected because the claimant's condition does not match the ones laid out in the policy - or the condition is not severe enough to qualify.
The industry accepts the number of rejected claims is too high and is taking a number of steps to change things.
The major providers of critical illness cover have started publishing their claim rejection statistics.
In addition, the industry body, the Association of British Insurers, has drawn up two new codes of conduct for its members.
One is designed to make the completion of application forms more straightforward. The other aims to standardise the list of qualifying illnesses.
BBC Radio 4 listener Dean Turrell took out a critical illness policy in 2003.
In 2004 he had a heart attack. But his insurer rejected his claim and he had a three year fight to get his pay out.
Dean Turrell joins presenter Lesley Curwen to get answers about the insurance product which caused him so much grief and to find out whether the industry reforms will make it easier for others to get a fair deal.
BBC Radio 4's Inside Money was broadcast on Saturday, 28 July 2007, at 1204 BST.
A longer version of the programme was broadcast on Monday, 30 July 2007, at 1502 BST.
Presenter: Lesley Curwen
Listener: Dean Turrell
Producer: Martin Bedford