Should one keep silent about a colleague who took an air conditioner from his workplace to his home, given that I had previously taken an internet SIM card and a delivery service from him? Is what I did by taking the SIM card considered unlawful? And is it valid to accuse me of ingratitude?

It is not permissible to take the air conditioner home without the company's knowledge, nor to use the internet SIM card and the car except according to the company's regulations and conditions. You must advise your colleague and enjoin upon him what is right and forbid what is wrong, in return for the favor and in preservation of rights, especially concerning matters of the Hereafter.