For anyone seeking professional advice from an immigration adviser, there are various independent bodies which can help. The government keep a list of useful links on the Find an immigration adviser page of the gov.uk website.
Registered immigration advisers
For anyone seeking advice from an immigration adviser, the Office of the Immigration Services Commissioner (OISC) is an independent public body which can help. You can also find help via The Law Society across the United Kingdom.
The OISC provide information about immigration advisers and the kinds of help that they can provide you with your application. You can get more information, and search for an adviser, on the OISC website.
The OISC also regulate immigration advisers and prosecute advisers working illegally. As part of this they accept and investigate complaints about anyone giving immigration advice, regulated or not. You should contact the OISC if you are concerned that you have been given bad advice, or you have had an application damaged by advice you have received.
You can get information from Citizens Advice on their Immigration page. Citizens Advice is a charity dedicated to providing clear information and guidance on your rights and the law.
There are many other charities and organisations which provide representation and advice on immigration matters. Many of these are small and help local communities, or people with specific issues, and can be found locally.