Is it permissible to inform the factory owner of a number of products less than the actual number in order to lower the agreed-upon price to the customary price, given his refusal to sell the products at the customary price?

If the questioner is an employee of the factory owner, it is not permissible for him to conceal the true quantity of goods from the factory owner for fear of a price increase, and this is considered a forbidden betrayal. However, if the questioner is a customer, and he agreed with the factory owner on a specific price and the sale or contract was concluded, then the factory owner is not allowed to increase the price thereafter, and the customer is not obligated to pay the increase. If a stratagem is necessary to repel injustice, then there is no harm in it. But if the sale has not been concluded, and there was collusion and a promise to sell, then the seller has the right to withdraw from the promise if he will incur harm due to rising prices.