Bad customer service and price fixing

i went to the garage yesterday to buy the Vienna,when i check the price on the fridge it was R8.50 and when i pay for it the till price was R10.00. I ask the trainee cashier by the name of Lusanda Mateyise why the price change. she shouted at me and tell me that I'm the only client complaining cause the rest of other clients they don't mind to pay for upper prices when they buy those vienas. I was so disapointed as we are getting ****** and being treated like dogs especially by the cashier at the garage. the manager must deal with that cashier as you will be losing a lot of clients.