STRATUM NOT PAYING

Hi all, very unhappy with Stratum gap cover, had a knee replacement and tried to claim back my portion of That the Discovery did not pay, the hopital shows the amount I paid on my account but Stratum says that is not good enough, they want Discovery to show the amount in the claims history, Discovery says it can not be done , I as the long term Member of both Discovery and Stratum , standing in the middle and short of R21800.00