Hello, I hope you are well. My name is***** am a solicitor advocate and I will be assisting you with your question today. I am very sorry to hear of the problem you are experiencing and I will do my best to help you with this matter.
I am sorry to hear of the issue caused by you neighbour.
You have already started the correct course of action by contacting the council.
If the neighbour has breach planning permission, then they do have the option of applying for retrospective permission. This you can of course object to. That would go to a hearing and the council would then decide whether to grant that permission, or order the extension be remove.
The fact that the neighbours are solicitors would have nothing to do with the case.
You could seek independent legal advice to represent you with a formal complain of nuisance etc. I would suggest a property law firm to represent you.
It may be helpful to instruct a local solicitor who specialises in this area of law. You can find a local firm using the Law Society website. www.lawsociety.org.uk
Once on that website, you can click on the find a solicitor option located just above the Law Society logo. Select quick search, then select the area of law required and enter your post code. A list of local firms will then be displayed.