Since my name was mentioned, I will comment something.
To address the comment about Unsimple scamming other developers, I don't think it's true. I've already done a lot of work with Unsimple, of course there will be mistakes on some occasions in a cooperation like this (in my case the mistakes were mostly on my part due to lack of experience), but in general I've never had serious problems working for him and I recommend it if you are a developer and looking to improve your skills in a frequent work environment.
Now about the topic, as we all know, Unsimple is a group of several developers and each project depends on their availability. I read part of the conversations and the biggest problem was poor communication between both parties and the unavailability of the developer related to WizardCP. If this were my decision, I would agree to a refund based on the unavailability of my team and missed work deadlines (it would not be a 100% refund obviously, since most of the work related to the front-end and design team was carried out).
I hope the two parties can resolve this matter.