Authorisation given by medical aid, no payment

Authorisation was given by Medscheme for a procedure during an operation - now they don't pay the hospital account and in the meantime I did receive a final notice from the hospital to pay the account and legal steps would be taken against me and I'm going to be put on a Black List. This was follow-up with them several times but to no avail, each time they promise that the matter will receive attention, but uptill now nothing but promises, and if they have system problems they need to sort it out . This is very poor and unacceptable service!!! I need them to resolve this now!!