Disappointed with Sour Milk and Poor Service at Usave in Zone 6

I recently purchased milk from Usave in Ga-Rankuwa Zone 6, only to find it was sour. When I returned the product, the cashier/security guard mentioned that the manager had been instructed to remove the product from the shelf after a previous complaint. Clearly, the staff is not paying attention to instructions, as this issue has occurred again. The manager offered a refund as if this was a common occurrence, with no action taken to prevent future incidents. This lack of accountability and poor service is unacceptable.