Guardmed Ambulance service unfair

Guardmed never submitted invoice to medical aid for the reason that the "medical aids never pay for call out fee", which I do not believe. They were eventually paid for transporting my mom the next day, but the call out fee of the previous day remained outstanding because they never subitted it to the medical aid..The next communication is that the debt collectors are handling the account and that they also demand fees for their services. I am disgusted that I was treated this way by Guardmed. I offered to pay the call out fees minus the debt collectors fees, but they refuse. They are holding me responsible for that fees as well. I will not use their services again. Thank you.