IAPT Tax and NI Reclaim if worked non- NHS

Hi all- HELP needed! There are so many people that have completed work related training within IAPT mental health teams but were employed via 3rd sector organisations/ charities and are stuck unable to claim back NI/ Tax whereas NHS counterparts are being rewarded for doing exactly the same job and training! Annoyingly I have done PWP and HIT training all with charties so am missing out big time. All of us were funded by health authorities from the same pot of money from Dept of Health. People have written to HMRC, employers, MPs and are getting nowhere....any guidance is welcomed, or if anyone has found a way to get their thousands back then please share as the clauses are making us excluded which is UNFAIR!