All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
If the companies that you mentioned are public companies belonging to the government or private companies but the people in charge of these companies are not authorized to take anything in return for those transactions, then in principle it is not permissible to give them money even if this is not to achieve falsehood or invalidate a right.
However, if the people's state is corrupt and the matter of fact is that the person who has a right either pays money or he will not be dealt with and his business (trade) and work would be ruined, then it is hoped that he is excused regarding what he pays and that the sin would fall upon the one who obliged him to pay.
Al-Qurtubi said in his Tafseer (interpretation of the Quran):
“It was reported that Wahb ibn Munabbih was asked, 'Is bribery absolutely forbidden (in all cases)?' He replied, 'What is dispraised in bribery is to give a bribe in order to get what you have no right to or to avoid to pay a right that you are obliged to pay. But to bribe in order to defend your religion, your blood and your wealth, then this is not forbidden.' Abu al-Layth As-Samarqandi said, 'This is the view that we adopt. There is nothing wrong for a man to pay a bribe in order to repel injustice from himself or his wealth.'”
Shaykh Ibn Taymiyyah was asked as in Majmoo’ al-Fataawa, “What is your opinion on a man who gifted the Ameer (ruler) a gift in order to request a need, to get closer to him, or to work for him and the like?”
He answered:
“As for a gift in intercession, such as to intercede for a man in order to repel injustice from him, or in order to make him get his right, or to appoint him in public office which he deserves, or to use him as a fighting soldier while he deserves that, or to give him from the endowment money that is assigned for the poor or the scholars or the reciters of the Quran or those who are devoted to Allaah's worship and the like, while he deserves that, and similar intercessions in which there is help in performing an obligation or abandoning what is forbidden, then it is also not permissible to accept a gift in all such matters, but it is permissible for the one who offers the gift in all this in order to achieve his right or repel injustice from him; this is what has been reported to us from the Salaf (righteous predecessors) and the prominent scholars.”
For more benefit, please refer to fatwa 83777.
As regards the issue of convincing the companies and attracting them to Islamic insurance, then this is a righteous deed and a good intention for which you will be rewarded, Allaah willing; and we ask Allaah to help you in it.
However, if the companies are private companies, and the decision-makers in it are its owners or authorized people who are given the permission to take what is given to them, then, in this case, the money that is given to them is like gifts and commercial incentives which the traders and businessmen offer in order to encourage customers to choose to deal with them, and this is acceptable.
Allaah knows best.