How to Cancel a Waterfall and Retrieve Credits in Clay

Hey! I ran a waterfall to get emails for around 500 contacts, I've gotten some but many are still queued. Is there any way I can cancel it, get some of the credits back? It's been like this for almost two hours and I don't think it's loading any more. I have closed clay, reloaded the page, let it sit, and went out of the table and went back in. If anyone could help me that would be great.