Unpaid invoices and tired of follow-up

I am really tired of Discovery and have to keep on calling to get invoices paid that my kids was admitted last year May and June.I have been calling and they keep saying they can only log a ticket for 6 payments at a time.every time it's a new reference or excuse. MY OTHER daughter had been admitted to hospital and I kept oncalling since sep and Discovery said it was paid for the ER.3 weeks ago I called again and the consultant said it wad paid today I get another message and when I call discovery they said it was not paid I am so confused and that it's not covered yet I was told if she was admitted everything was covered.Today I have new references *** and ***