Short Paid Claim - Conflicting Information

Practice Number *** Date of Service 20 - 22 March. Our son was admitted to Hospital with bronchopneumonia we took him to casualty as he was having difficulty breathing and the Trauma Doctor admitted him. We understand that we have been reimbursed at 200% Discovery Health rate for some of the procedure codes, however when we queried further amount the amounts being paid in full we were advised to send through a motivation letter. A motivation letter from which doctor, the PAED or the Trauma doctor? Where do we send this letter? Why is it necessary for the Motivation letter whereby the ICD10 code states the diagnosis. Due to the fact that this is a PMB and an emergency please would someone contact us and give us correct information as to the reasons for the short payment and clarity on the motivation and from whom. We have been given different information from everyone we speak to. Thank you