Specsavers Insurance on special offers

Specsavers Brits Mall I got specs on the mzanzi special, bi focals. Total cost including the INSURANCE R1098 I lost my glasses and went in to claim, the lady informed me that I now have to pay in on the claim R1098.00. The original cost of the glasses, how can this be correct. 20% of R1098.00 = R1098.00 according to the lady. Am I now paying for hidden costs on the special offered. What is the point of selling me insurance that does not cover special offers. Johan Venter