Should one forgive or pray against a saleswoman who defrauded one of a small amount of money and took the price without delivering the products?

It is permissible to supplicate against an oppressor to the extent of their injustice. However, forgiveness is better, unless it leads to the oppressor persisting in their wrongdoing, in which case seeking retribution is preferable. Allah Almighty says: "So whoever pardons and makes reconciliation - his reward is due from Allah." And the Prophet, peace and blessings be upon him, said: "Allah increases a servant in nothing but honor by his pardoning." Supplicating against an oppressor is considered a form of retribution commensurate with the injustice. If forgiveness leads to an increase in oppression, then seeking retribution is more appropriate. But if the wrongdoer's mistake is minor, then forgiveness is better.