Maybe people that have been in the same situation? Why post on a thread you have no experience or can contribute any help to?
You've settled your claim, is that correct? In which case you'll be outside of many time limits for bringing another.
If at any stage prior to accepting, you felt you were getting a raw deal, then was the time to say so.
Once you've agreed settlement, your options are limited. You could always take those, that you chose to represent you, to court. But that might mean having to pay back any monies gained, before starting such action. You then have a two way fight on your hands. One for the initial case(those parts you can still claim for) and proving the standard of service was below the expected level for which you were paying.
The Law Society has a system in place, but you have a lot to prove to them. Not easy, but doable. Assuming that the other side don't want to make a case of it, and are happy to pass their paperwork onto someone who will then be acting against them.
Just hope you have everything written down. Times, dates, names & numbers, as a minimum.