Is it permissible for a female lawyer to demand an increase in her fees after the verdict has been issued, especially if the agreed-upon fees were less than what is customary, and if it becomes clear that the increase is unlawful, what should she do with the excess money?

What is considered valid for a wage or price is what the two contracting parties have agreed upon, even if it contradicts custom, due to Allah’s saying: "O you who have believed, fulfill [all] contracts," and the Messenger of Allah (peace be upon him) saying: "Muslims are bound by their stipulations."

Accordingly, you are not entitled to take a fee exceeding what was agreed upon in the lawyer's contract, and it is not permissible to raise it under the pretext of the opponent's wealth or the agreed-upon fee being low compared to what is customary.

If you have taken an excess amount, it must be returned to its owner unless he agrees otherwise, based on the Prophet's (peace be upon him) saying: "Every Muslim's blood, wealth, and honor are sacred to another Muslim."