Paying money that was not initially on quotation

I bought specticals at torgar optical in brits mall where by de eye care specialist told me my prescription is to high had to pay 2800 for my lens including the frame..than the receptionist calls a few hours after tell me that there was an amount of R350 that I have to pay that she didn't include on the quotation on fine told her will see her when the glasses arrive..so now the day I went to fetch my glasses they tell there's an amount of R700 meaning R350 for each lens that I have to pay for an anti scratch glass of which they didn't even ask I wanted it or not and the last who was testing my eyes didn't even say it's compulsory or not...since I was desperate for my glasses had to pay such an amount of which I don't know how it came about and to avoid arguments...I feel cheated on because that money was not on my budget had to use transport money...bad service indeed