Have you checked the key topics in this forum and the many existing threads on low charges personal pension and PRSA products? As a rule of thumb standard PRSA charges are capped at 5% of each contribution and 1% annual management charge and no other charges. You can also get lower than this on standard PRSAs or personal pension plans (RACs/Retirement Annuity Contracts) from certain sources (e.g. flat fee charging discount and usually execution brokers/multi agency intermediaries if you shop around. Pay higher charges than these at your peril or only if you can see some real, tangible benefit in doing so.
Are you sure that the pension scheme is actually charging 50% in some or all cases? I find that hard to believe. Even if it is were these charges divulged up front to employees who joined? If they were and they joined anyway then they are not being ripped off since the went in willingly and in full knowledge of the charges levied. If they were not divulged up front then members should raise a fuss about this and maybe contact the Pensions Board.