Failure to supply documentation timeously

My son was hospitalised in November 2015 for a respiratory infection. The attending pediatrician requested a test from Lancet which was done. I became aware of the test only after my medical aid statement reflected non payment. I contacted the medical aid, who informed me that the incorrect procedure code was used and they would pay if I submitted the request from the pediatrician for the test. I contacted Lancet, who supp**** the documentation after 2 months of reminders, along with an internal memo from Dr Peter Cole stating the problem with using this code. My medical aid has now refused my claim on ground of age of the claim. I will pay the account, however I would like to know how Lancet as an assumed professional company do not inform patients of the problem between themselves and the medical aid before conducting expensive tests, and then fail to supply the patient with documentation timeously in order for the patient to be able to claim from their medical aid. The problem is also compounded by call centre agents and managers not responding to queries promptly and efficiently