I saw your post on Kopitiam at Lau Pa Sat overcharging customer.
I met with a case today too. I was at Kou Fu at Jem. The menu signage stated $1.70 for ice lemon tea. So I ordered 2.
I took out $4 waiting to pay my drinks. But this China cashier told me its $4.40. So I took out another $0.40 from my wallet.
I found it puzzled and asked the cashier.
Me: The menu stated $1.70 (pointing to the signage), why is it $2.20 per cup?
Cashier: $2.20 is for large cup
Me: But you didn't ask me if I want large cup.
Cashier: We always push large cup. (She literally said push, so basically forcing customer to pay for large cup.)
Before I could ask for a change to regular cup at $1.70 each. She ignored me and was serving the customer behind me. I left the counter feeling cheated.
As I typed this, I think I should probably insist that I want my regular cup of ice lemon tea instead.
This is so unexpected in a foodcourt in Singapore. The cashier decided for me that I want the large cup without asking me.
After I questioned her, she just pushed the receipt to me. But I threw away before I saw this post or else I will take a photo for you too.