FLR(O) waiting 4+ years

My sister has been waiting for over 4 years now for her FLR(O) case. She applied under medical grounds in 2012. In 2012, they refused and she appealed. In 2014, first-tier tribunal allowed our appeal. In 2014, they again refused and she again appealed. In 2015, her appeal was allowed by the first-tier tribunal. In 2016, they called her for an interview, where she was asked about an English test that she had taken. The test wasn't submitted as part of her FLR application. Our local MP has been assisting her since 2016, querying the Home office about her case. The Home office assured that they would give a decision by October 2016, but even that hasn't materialised.

So she has been hopelessly waiting. I would like your view or advice on whether it is worth waiting any longer? Obviously, it has been a long wait. But, where should she seek help at this point?

Has she seen a solicitor? Sounds like a case where it would be useful to see if a pre-action protocol letter for Judicial Review might spur someone into action.

Thanks for your comments!

Her case was handled by a solicitor all through. However, after the last judgement was made (which was in her favour) she hasn't contacted the firm and the firm also no longer represents her. The file needs to be re-opneed with them for a fee.

What is a pre-action protocol letter? Surely, this has to drafted by a solicitor and sent from their firm?

It's not an absolute requirement that a solicitor drafts it

Anyone can draft the letter before action. It is a formal notice that you intend to take another party to court.