Do frequent changes in the contractor's terms, and the refusal to treat a work injury, negate the worker's right to claim before God, because he agreed to continue working despite the violations, due to the unavailability of other work?

If the company violates the terms of the contract, you are permitted to annul it, due to one of the parties failing to fulfill their obligations. However, if you agree to continue despite the violation because no alternative is available, you are bound by what you have accepted until the term expires. After two years, both parties are free to maintain the same terms, change them, or cancel the contract. The advice offered to them is to fulfill the legitimate terms of the contract, in accordance with the Almighty's saying: ﴿O you who have believed, fulfill [all] contracts﴾, and the Prophet's (peace be upon him) saying: "Muslims are bound by their stipulations."