Is the price at the checkout higher than on the price tag? The store is obliged to sell the product at the price indicated on the shelf or refund the payment in excess, - SYUG.
If the price tag is 80 UAH, and at the checkout they demand 110 UAH, the buyer has the right to pay 80 UAH.
The seller's explanation that "they didn't have time to change the price tags" or "the price has already changed" does not exempt the store from responsibility.
If the product has already been paid for, you can request a refund of the difference.
For proof, take a photo of the price tag with the product name and keep the receipt.
If the store refuses, contact the manager or file a complaint with the state's production and consumer service.