Is it permissible to take one's right from an institution without its knowledge, given that the questioner works as an accountant in a charitable institution whose salaries have not been updated for 8 years, and which adjusts the salaries of other employees based on favoritism?

Allah commanded the fulfillment of contracts, and the Prophet warned against not giving a laborer his full due. If a laborer does not receive his full agreed-upon wage, he is permitted to take it by any possible means ("al-Zafar bil-Haqq" - gaining possession of one's right). However, if an employee receives his full agreed-upon wage, but believes he deserves more for other reasons, he is not permitted to take anything beyond what was agreed upon, and doing so is considered betrayal and deception.