Explain this: Bedok stall charges different prices for 3 pratas in same order

Three pratas, two different pricings, but all in one order: Something is not adding up.

Stomper Dan said his domestic helper was unreasonably overcharged for three pieces of plain prata.

The helper had visited the stall at Block 203 Bedok North Street 1 on Jan 1, at around noon.

Dan told Stomp: "She ordered three plain pratas for takeaway, but was charged different prices. All three pratas were packed together.

"The stall owner didn't explain why. My understanding is the price for one prata is $1.40 and more than one piece will be the normal price of $1.20.

"It's not the first time this has happened. It's an unreasonable overcharge."

Can you make sense of the bill?