The insurance companies can do anything they want. They couldn't have a patsy without the GOP lying about the ACA and stupid Right-wingers dumb enough to believe them.
Ah... so you
don't understand. Well, I can explain it. It's fairly simple. Thanks to the ACA, insurance companies aren't allowed to write any new policies to replace those that don't meet the new minimum requirements.
They can grandfather the old policies, so technically they could let people keep those, but they make a lot more money from the policies that do meet the new guidelines. So they're cancelling the old policies and people are then forced onto the more expensive policies.
They could have still tried the same thing, I suppose, without ACA, but competing companies would have been happy to write policies to replace those that were cancelled - scooping up their former customers.
But with regulatory capture, other companies aren't allowed to do that. So they have us by the balls, thanks to Congress selling us out.
Does that clear things up?