How can one deal with a driver who used the company's fuel card without its knowledge for his personal benefit, and pledged to return the amount, while retaining his job? Is it permissible to take the amount and use it to repair company cars without informing the management?

The worker erred by using the company's top-up card for his personal benefit, and he must repent and return the amount he spent to the company in a way that does not harm him. If he is unable to return the amount in cash, then it is permissible to return it in the manner mentioned by the questioner, due to the Almighty's saying: "So fear Allah as much as you are able."