Spec savers get your act together

For 6 years I have been going to Spec savers in Newcastle we drive 70km there and 70km back and we never had a hick up. We can use our optometrist were we from, but we use to get good service from spec savers newcastle until 3 December, we made our appointment they assist as normal, then when I was done I asked the lady which section of the glasses will my medical cover so she showed me, I chose my glasses and we were set waited 40 min for her to finish my estimate or proof of order. Then my partner was finished same story the same glasses frame from the same section was assigned to us. So now today the 5 th of December they call to say the glasses that we selected was not the grey section it was the brown section and I have to pay in R 400. And they sorry the glasses were mixed up. So who's fault is it that they were mixed up. Not mine, No I don't think so.... I will not pay the sort fall because my medical coverd the complete estimate that was submitted. This is not on. Then I said I would like to speak to the manager the lady don't even mute the phone I hear her whole conversation with another person.