How can I stop a bot from placing abandoned orders on my ecommerce site?

Right now the issue is bots running credit cards. They are testing credit cards across shopify sites because shopify isn’t doing anything to stop them. They should add a captcha to check put page. High negligence on shopifys part to allow this go occur. You can change to require customer to log in before check out but that I’d a conversion killer. We need to all get together and demand they fix it.