storm not refunding my store credit

Scammer's profile link: idk... Talking about the old Storm client
Amount scammed: According to my calculations it's around 938 EUR
Discord ID + Unique Discord ID:
Proof that it's their Discord:
Explanation of the trade: I spent 1000 EUR to get 100k credits on their site. Jagex requested them to shut down, they complied. Then I was able to message one of the moderators, first he seemed really helpful, then he ignored me. I think they owe me a refund. This is for the store credits, I know they do not owe me anything I actually spent on their site.
How they scammed: Never refunded me.
Other relevant trade screenshots: