NETCARE 911 *******

I was taken to hospital by ER24 after a motorcycle accident. i received a bill from netcare 911 stating they assisted me which was not the case as my parents were on the scene and ER24 assisted me. after a while i called and tried to get this resolved,I was told that i should pay if i did not receive a bill from ER24. I used their online system to make a payment. Later i received an invoice from ER24 which i paid as well but netcare hasn't refunded me as they cant find the payment. I keep on getting calls from debt collectors insisting that i owe the money. i cant send a proof of payment as i used the online system to make payment. when i go to the online statement it has my invoice number with "Fully paid" message. they will not accept this as proof from their own system. i sent through a screen shot of my credit card statement highlighting the transaction with no avail.