There are a number of services in the UK that are completely free to use. They are there to help explain your credit report and financial situation, and how to improve it (listed below).
However, it is important to be careful as, whilst there may be some companies that will genuinely want to help, there are many repair companies that can often act in an unethical and illegal way.
If you need advice on dealing with your debts, you can get free help from any number of debt counselling or money advice organisations:
Citizens Advice Bureau – https://www.citizensadvice.org.uk/
Consumer Credit Counselling Service – http://www.stepchange.org/
National Debt line – https://www.nationaldebtline.org/
Money Advice Service - https://www.moneyadviceservice.org.uk/en