Conned for a 10% price hike at KFC

We eat KFC 3/4 times a year so not fami**** with menu. Stand at counter look at menu see : Lunch Box R49.90 food and small cool drink. Wrapsta Box R49.90 food and small cool drink. I think MMnnn ya ok hundred bucks, wife and kid are happy, One Blue note done. Give order an lady asks glass or bottle ?, I answer bottle, I can reseal it and easier to transport home. I put my R100 down and cashier tells me R109.80 HUH ? 10% jump in price. I tell her menu displays R49.90 she replies yes but only for a glass R10.00 more if you choose the wrong option which was offered, I did not ask for a change in menu - I ordered a item by name I was asked which I wanted - I thought it was a choice, not a menu change. So now I am ****ed already, and I know my temper, there are people standing waiting watching, what now ? do i make a fuss about R10.00 manipulated out of me , do I walk out and have tears from kid ?, or do I just allow myself to be ??? what conned - *******, slicked - what just happened ?? In one move I was put in a position of embarrass self or cough and pay ? So here I am - I am ****ed off , you did me, very cleverly. I want to do some thing - I want to lash back >>>>>>>>>>>>>>>I am angry cause I know I am not the first second or 50 th person to be put in that position, most people just say nothing though.