Is it permissible for a subscriber to increase their internet speed to more than 128 kilobytes by a specific method, knowing that they pay a fixed monthly amount, that higher speeds from the service provider cost more, and that the company's contract does not prohibit the user from doing so?

Contracting with a telecommunications company for internet service is a lease of usufructs, and the terms of the contract, the known benefit, and the agreed-upon rent must be adhered to. Increasing the service duration or the number of users without the company's permission is considered an unlawful encroachment on its property, and people's wealth cannot be taken except with their consent.