Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering your question, Prof. Dr. Monzer Kahf, Professor of Islamic Finance and Economics at Qatar Faculty of Islamic Studies, states:
Unfortunately, this commission practice in respected service-provision professions has become a very bad culture in some countries. We must all fight it and stand against its practice.
Those commission givers should be boycotted, whether the bills are paid by insurance companies or by the patients themselves.
Even if the bills are paid by insurance companies, they end up raising the final payment by patients.
It is a bribe, no doubt about that. Giving it and taking it is not permissible, and if taken because some labs and pharmacies give it anyway, it should be rendered to the customer/patient or the bill payer (insurance companies).
Allah Almighty knows best.