How can one repent from using a company phone without permission for personal calls, especially since the value of these calls cannot be determined or paid at present? And is it permissible to consider the deputy manager's use of the questioner's data without his permission to import cars as equivalent, so that the money does not need to be returned?

An employee is not permitted to use company devices for personal purposes without permission, especially if this incurs a cost. Whoever has done so must repent to Allah by returning the value of the calls, or by informing the employer and seeking their forgiveness. It is not a condition to inform them; it suffices to deliver the money to them by any means. If the money is not available now, it remains a debt and must be paid when possible. Compensation can be demanded for the use of one's name to import the car, and then the rights and obligations are offset. However, offsetting is not permissible without informing the company owner.