NONE PAYMENT/NO RESPONSE

After admission to hospital in May for surgery, all accounts except one was paid. The doctor's account, that was sent to Discovery by the doctor's rooms on 6 May 2015 is the only outstanding account. After I had sent the account through on two occasions, I have not received any communication from Discovery regarding the non-payment, nor have I received any proof of payment that was made. What would the reasons be? I do not have any answers for the doctor and do not wish to enter into a non-payment dispute with my trusted doctor. Please attend to this matter with urgency.