Discovery's customer service is exceptionally poor

I have made 5 very long phone calls in an attempt to get my (my husband and my) tax certificate for the 2015 tax year (the last tax year). Discovery keeps sending through a certificate with a minimal amount on and which does not reflect what appears on my statement of account. Finance appears to be the breakdown as they generate an automatic certificate. I therefore requested a manual certificate yet this has not been actioned. If you look at my statement of accounts it is very clear that there are a number of items listed which are not accounted for in my tax certificate. I was previously advised that these invoices did not have the correct Nappi codes and therefore made the effort of going back to the doctor to acquire these. Since doing that his invoices reflect on my statement of account however not on my tax certificate. Come on Discovery. This is not rocket science. We pay you every month on time and when we want some much needed information from you, one simple document, you cannot provide your diligent customer with it. Make it happen promptly please!!!