Sue them for lost interest. You should have a strong case in principle, however, in practice, it's most likely not worth it for you (which is the real reason why this is happening). But if you have a lawyer friend who can give a first opinion for free, you could give 'em a call.
Sadly, because you are incorporated, I do not think you can go the small claims court route. Maybe hit up the legalist for funding and or check with an attorney who does financial class action in San Francisco. You are probably not alone and considering the nature of your business being small, you may have a claim that it destroyed your operations and ability to earn(which they probably did in reality). *Not a lawyer and not legal advice.
Their ToS probably gives them wide latitude to arbitrarily freeze funds without having to compensate you. Not to mention, any lost interest pales in comparison to any legal fees. The federal funds rate is currently 3.08%. Apply that over 120 days and it's only 1.01%. If a lawsuit cost $10k (very conservative estimate), you'd need to have 990k frozen by stripe for it to be worth it. Even if all it took was a sternly worded letter from a lawyer (estimated cost: $300), you'd to have $30k frozen for it to break even.
ToS aren't law, what matters in court is what the judge decides, and they can decide that certain ToS terms were never valid. But the question is whether it makes financial sense to do so, where for most accounts the answer will be no (hence why providers can get away with it for a long time).
There are also some small chances that the company will try to reach a settlement to avoid a ruling that would give a lot of customers a strong lever before they can update their ToS (which could mean a much larger payout in return for signing some NDAs), that you are awarded additional punitive damages (pretty unlikely here though, I'd guess), or that you find a consumer rights organization that is willing to cover your legal fees. And of course, some people are willing to fight for their rights even if it doesn't make sense financially (this guy [0] fought and won a 22-year legal battle against Indian Railways over something like 20c).
