Best ways to stop corporations from dominating?

[FAA]

I’m playing as a meritocracy/commerce focused nation, which naturally makes corporations grow. It’s turn 20 and it’s already at 16 in my main province. How can I restrain them and their abuse? I can nominate a person to their board, I thought about nominating the governor, is that a good idea? What about taxes? The antitrust efforts won’t work as the difficulty is way too high.

[Jdane]

I honestly don't know and could also use a clue or two.

I managed to place two leaders in the Corporation's board, it looks it's smart enough not to give you a majority vote by allowing more.
Come turn 21 its control in the capital's zone is at 18% but it only siphons a smaller percentage of the private sector's income, damaging a little the population's happiness but that effect is balanced by other means.
Taxes only seemed for now only to bring back a handful of credits and decrease our relationship level.

I know for a fact from a previous game that befriending the Corporation can reward you with some Stratagems, but I'm yet to learn more about this story module.

[Soar_Slitherine]

Apparently the governor can choose to prevent them from increasing their control, which the tooltip says my governor is doing. The guy isn't anti-commerce in his profile or anything like that, so I'm not sure what the specific reason for that is.

[Kamelpov]

You can get anti corporation card if you want to purge part of the control

[Jdane]

My governor is on the board and accepting bribes from the Corporation for him to look the other way. [:D]