Client service sucks!

I recently received an account from Vermaak and Partners Pathologists, that stretched back to December 2014. I have now sent 5 email requests to Discovery to clear this up but I have not received one reply. My tests are supposed to be paid from PMB. I decided to phone Discovery and spent an hour on the phone with them. They assured me that the bills were paid and sent me a statement showing that. (They sent in the bills for reprocessing, stating that a payment was not made, because the bills had already been paid.) I sent it to Vermaak and Partners, who still insist that the bills were not paid. All they see is that no payment was made - they can't figure out that a payment was not made, because it had already been paid! They apparently spoke to a guy at Discovery named Nigel who told them that the bills were not paid - the opposite of what they told me. Discovery also insists that one of the bills could not be paid, because I need a specialist referral number, but I was approved for PMB, which should pay for all the tests. When I phoned them about this situation, the consultant I spoke to said he would reprocess the bill, because it would take to long to find the PMB approval letter on my file. So no-one has tried to find this letter and resolve the issue, because it is too much trouble!