Incorrect billing

I went to Spec-savers a few months ago. Had my eyes tested and needed my one lens renewed. They gave me a quote and said it will cost me nothing as the medical aid pays for everything. When I went to fetch my classes I was told I have to pay a R1600 to get my glasses. I showed them the quote I got from them and they did not care. I did not had the money to pay for this and still don't. I am in the process of being retrenched and in the interim they have handed me over but up till then did not even met me half way by giving me some discount because of there error. Had to work without my glasses for the last few months. Suppose I will have to use the little money I will get out from retrenchment and pay for the glasses. Disgusted in their service and will never go back to them again. Not referring anybody to them as well. Always thought they are a reputable business.