The day you decided to go with Stripe you started being hostage of them, but this is not a bad thing, this is business, you choose a partner, they are allowed to change the terms if the contract permit it.
People on HN always think they deserve to be treated better than others
I have noticed a significant attitude of, "I originally signed up for this product with 'x' cost and 'x' features, and you have zero right to change anything about that."
It seems like a basic contract negotiation process would ferret that out - I thought that was a business thing to do. I work in higher ed, and we absolutely have to have contracts for all third-party vendors; any changes are negotiated with the start of new contracts. If we can figure it out, surely startups can - we're not really all that good at efficiency.
1. Stripe
2. Braintree
3. Coinbase Commerce
4. GitHub Marketplace