Incorrect Billing date

I had a procedure done in hospital on 23rd September 2015 which would have been completely covered by my medical aid. However Lancet accounts have put the date as 28th of September 2015 (I was discharged on 26th September 2015) with the result I have exceeded my out of hospital specialist benefit which would not have happened if the correct date had been entered. I have contacted Lancet both via email and telephonically and apart from being told 1. The date on the statement is correct (Mr Kenneth Brewer email) + I must pay the account, 2. Telephonic wiTh Michelle - Lancet made an error + will rectify. 3. Email from Alistacia Mapping to state \that the account has been sent to the relavent department assist with the enquiry for the service date."4. Sms's with incorrect statement + daily phone calls when the accounts department hangs up when I answer. I call back + am asked if I am aware of the outstanding amount. I then explain the whole situation to them again. After nearly 2 weeks of trying to get this matter rectified I have had quite enough of Lancet accounts total incompetence and trust that you will be able to help me get this issue resolved."""