Complaint about an invoice

My father was admitted at the Medforum hospital and they have since sent me 2 invoices for the emergency unit and 2 for ICU. Medclinic insists that the invoices dated 18 and 19 August were sent in error and they are preliminary invoices. Mediclinic are abusing private clients, the invoices changed as soon as Discovery declined the amounts and i was firstly charged private clients fees, then the story changed to the invoices were preliminary.<br> <br> Emergency Unit account<br> The initial amount (dated 18 August 2015) : R2,698 <br> The revised invoice (dated 7 September 2015): R2 832 <br> <br> ICU account <br> Invoice date 19 August 2015 : R7,532 <br> Invoice date 04 September 2015 : R17,543.30 <br> Invoice date 04 September 2015 : R10,920.00