You have entered a tail spin of serial refusals. You have lost the first two refusal notices (that's a bad thing) and have posted a scan of the most recent (that's a good thing).
The refusal notice, along with your text, offers a glimpse into what's happening from which some assumptions can be made, the most prominent of these are...
- you do not understand how to qualify for a Standard Visitor Visa;
- you will continue in the situation of serial refusals until you get
some professional help;
- In the most recent refusal, you failed to establish a believable
premise (V 4.2 a+e)
Serial refusals are bad because they feed off themselves and it can be an uphill battle from square 1. Also, it's time to be a little bit careful because if a person is getting serial refusals they have the option (but not the obligation) to lay down a ban under Paragraph 320 or 321.
how can I get help from a registered solicitor?
UK Solicitors can develop a practice area accessible by the general public when they are admitted to the UK Law Society. Once they have this qualification, they can be 'instructed' by an individual to help out. The Law Society offers a search engine which is keyed by practice area (obviously you want 'Immigration'). You can select a few and send them some emails and see if they can take you under client care. You will have to agree a fee with one and make a substantial retainer as a prerequisite to instructing them. Solicitors do not do pro bono work for visit visas.
On the plus side, they will not take you on if they don't think there's a good chance they can win. On the down side, your case is going to be bloody expensive. I am guessing about GBP 3,500 as a stab in the dark, but that's a guess only.
Alternatively, the Immigration Services Commissioner can also enable a person to help represent you. These people are called "Immigration Advisers", and the Commissioner has a list of them on her site: Office of the Immigration Services Commissioner. Immigration Advisers do not have the same standards of membership rigour that the Law Society does, and so the risk of taking you under client care is less. They are also less likely to have credible standing with the various ECO's out there to ward off any problems when an ECO is minded to refuse. But they will still want to be paid, and I am guessing in your case the fee would start at about GBP 800, but again that's a guess.
Sometimes a practitioner has developed a standing in the profession where they can get approved to join the Immigration Law Practitioners' Association. This association operates a paywall that has all of the latest policy and correspondence with Parliament and the Home Office. They operate a search engine of their members that you can use. Note: the practitioners listed will either be a Law Society member or have a certificate issued by the Commissioner (because those two groups are the only people who can lawfully practice).
And finally, if you have a situation that is hugely interesting as a matter of law and the outcome affects a lot of people, you MIGHT be able to get the JCWI to take you on for free. I doubt they will given what you wrote, but there's no harm in trying. Use the Joint Council for the Welfare of Immigrants to post an enquiry.
That's four options. I don't recommend using the net because serial refusals are almost too impossibly complex to get all the relevant details.
So the best advice is to come to terms with the fact that you will need to pay and then to use the search engine at ILPA. All told there are fewer than perhaps a dozen or two out there with a strong practice area in serial refusals for visitors so you will need to plan for an appropriate amount of time to search.
Footnote: Immigration advice in the UK (and EU) is a closely regulated activity. Section 84 of the Immigration Act 1999 makes it a criminal offence to provide immigration advice unless the practitioner is a member of the Law Society or has a certificate from the Commissioner or has an exemption. And they do prosecute. This protects people from being scammed and assures the help they get is high quality. There are counterpart regimes for the Schengen zone and the rest of the EEA.
Footnote: Colin Yeo (a barrister, not a solicitor) operates a application checking service where he will look over your stuff and tell you if it's up to scratch. This is a doc checking service and NOT representation (big difference). He charges a flat rate which is a curiously precise GBP 249.99. He's OK. There are some other doc checks out there that can be vouched for also, what they do and what they charge varies. Disclaimer: I have known Colin Yeo (and Ian Westwood) through stakeholder committees for a long, long time. Remember that a doc check will work for border-line cases; it will not work for a seriously complex one (like the one in this question).