Why does Specsavers ignore me?

I paid just over R2000 for a pair of prescription glasses from Specsavers online on 4 December 2017. I did not have my eye test with them but with an independent optometrist. I submitted their invoice to GEMS, my medical insurer, soon thereafter. GEMS requested further information which it appears Specsavers has not provided. It would be a real shame if I were left out of pocket as a result of Specsavers' incompetence and/or inability to assist. Please can someone help.