GEMS useless

I have been trying to call GEMs about my husbands chronic medication. he can’t access them because they told him he must go to a certain pharmacy and when he went there he wasn’t given. Again gems doesn’t give medication recommended by the Dr and their alternatives are not helpful to my husband as he used them before, does this mean being on chronic with GEMS is not useful as it should be because they hardly pay for most medications recommended by Drs? they always choose those that are not strong. Again, i get emails from Drs saying i owe them for my small child can i get an explanation?