Prices and receipts
Prices must be shown in Colombian pesos and include all taxes and extra costs. You only have to pay the price shown, and if two prices appear you pay the lower one.
You can ask for proof of every purchase at the seller’s cost; an invoice or equivalent serves as proof, but not having it does not stop you from claiming your rights.
Source: Ley 1480 de 2011 (Estatuto del Consumidor), articles 26 and 27 – official text
Prices at a food counter
Places that serve food and drinks must show the price of each product on a list posted where you can easily see it or on printed menus. An app or a QR code can only be an extra way to see them, and you must not be asked for personal data before seeing prices.
They must give you an invoice or equivalent document, not a pre-bill or order slip.
Source: SIC Circular Única, Título II, numerals 2.4 and 2.4.3 – official text