Bad Experience and unprofessionalism

I contacted Discovery to inform them that Dr Hogg and Partners had invoiced them for an amount that I had already paid to Dr Hogg and partners. I asked them not to pay the Dr as I had already paid and that I could provide proof. Discovery told me that they cannot help me and that they would still pay the Dr and that I must get the money I paid pack from the Dr. They lady from Discovery was very rude to me when I asked her why she could not stop payment. I was told those are the rules and they have to pay what the Dr invoices. I told the lady that I disagree because when your medical savings are finished, Discovery can then find a way to not pay the Dr what was invoiced.