Here are our top tips to help repair the damage:

1. On the record

If you are being treated like a pariah by banks and credit card companies, you need to establish the reason. All should be revealed by your credit reference file, which records your past borrowing behaviour. A copy of your file can be ordered online for a small fee from the websites of the three main credit reference agencies, which are Experian (www.experian.co.uk), Equifax (www.equifax.co.uk) and Call Credit (www.callcredit.co.uk).

2. Decide to take action

It is worth getting your credit rating back up to scratch. Moneysupermarket.com, the price comparison website, offers a “smart search” service. Borrowers can search for the best deals available according to their creditworthiness. Those with a poor credit history can expect to pay rates of at least 12 per cent for an unsecured personal loan — more than double the price of the best deals.

3. Beware of credit repair

Credit repair companies advertise a service that purports to be able to clean up your credit file. But these companies sometimes offer shoddy advice and charge a fee for information that can be obtained for a modest sum from credit reference agencies and debt counselling services.

4. Borrow to build credit

If you are invisible to credit agencies, your credit record will not be spotless. It could be worth taking out a credit card. Using the card wisely, without incurring charges or penalties, will help you to rebuild your creditworthiness.

5. Think the unthinkable

In almost all situations, store cards should be treated as the financial equivalent of nuclear waste. Interest rates can be a toxic 30 per cent. But, again, if you pay off the balance each month, simply owning a store card and using it will help to rebuild your credit rating.

6. On a roll

Lenders and credit reference agencies want to know where you live, so make sure that you register your details on the electoral roll. To do this, contact your local council.

7. Mobile credit

When you take out a 12-month contract with a mobile phone company, you are signing up to a consumer credit contract. Keep up with the monthly payments and your credit rating will improve.

8. County court judgments

If your finances have gone awry and you have county court judgments in your name, pay off the debt in full and make sure that records at the Register of County Court Judgments are amended.

9. Make your mortgage work for you

Even if your credit rating is low, you will still have access to a homeloan, although you will have to pay higher rates of interest. But if you keep up with your repayments for a couple of years, you are likely to become eligible for cheaper mainstream deals when you come to re-mortgage.

10. Further help

National Debtline (www.nationaldebtline.co.uk, 0808 8084000) and the Consumer Credit Counselling Service (www.cccs.co.uk, 0800 1381111) offer debt management advice.