What should I do about my salary being illegally reduced and being threatened with visa cancellation, knowing that the sponsor has strong influence and connections, and am I entitled to reclaim what was deducted from my salary if I get the chance?

If the tenant reduces the agreed-upon rent before the lease term expires, the lessor is permitted to take the difference without the tenant's knowledge if that is the only way to secure their right. However, if the reduction occurs after the contract ends and the tenant offers a new rent, the lessor is not entitled to take any increase beyond the agreed-upon rent, because they have not been wronged.