freaking pissed off

I'm so pissed off!
Last week, I brought my sister to an optical shop in Chinatown for cheap spectacles. A week later, I went to collect her spectacles and passed to her on Saturday. The moment when she tested her spectacles, she said it was weird. I thought she meant the specs were not adjusted properly. So I asked to go check it out herself. Initially, I wanted to ask her to go back to the shop in Chinatown, but considering the distance, I didn't press on.
Just now, before I went coaching, she sent me an SMS saying that she went to the optical shop in Whitesands instead and the person told her that the degree in her left lens were too high for her. So I thought I will meet her on Tuesday again to go back to the shop in Chinatown for a change.
Instead she replied that the person wanted to change for her. Feeling puzzled, I called her to clarify. Then she told me the person actually charged $20 for the eye test, and if she change the lens, it would be $40. My poor sister with no money at the crucial time, agreed to let them change the lens. TMD! I'm freaking pissed off by the fact that they didn't inform my sister beforehand that they will charge her for the eye test! KNNBCCB! Fucking assholes!
I hate it when we have to spend all these unjustified money!