Is deducting one and a half minutes from the call balance for mobile calls for every minute of connection, while the buyer is informed that they have 60 minutes in their balance, considered "cheating in the scale," and how can this be rectified given the need to reduce mobile minutes due to their exorbitant price?

What you are doing by deceiving the customer into believing that there are 60 minutes balance on the card, when it is less than that, is considered lying and cheating, which are forbidden by Islamic law; based on the Almighty's saying: "Then we would earnestly pray and invoke the curse of Allah upon those who lie" [Al Imran: 61], and based on the Prophet's (peace be upon him) saying: "Indeed, lying leads to immorality, and immorality leads to the Hellfire. And a man keeps on lying until he is written as a liar with Allah" (narrated by Al-Bukhari and Muslim), and based on the Prophet's (peace be upon him) saying: "Whoever cheats us is not of us" (narrated by Muslim).

Therefore, you must repent from this, and return the money you took through this method to its owners if possible, otherwise, donate it to the poor and needy. If you find its owners and they approve of your action, then that is what is required, otherwise, you must pay their money to them, and you will have the reward for what you donated. The alternative to reducing minutes through deception is to adhere to honesty and raise the price per minute.