Assuming you are UK based, you should have a case. UKGC will stand over you as they are UKGC registered. If you have no luck in the next few days, then contact the UKGC and let Peachy Games know that you will be submitting a complaint to them. 

You can contact the UK Gambling Commission   here : https://www.gamblingcommission.gov.uk/for-the-public/Your-rights/Concern-about-a-gambling-business.aspx

Hope this helps, and I hope and trust that you both get your money back and also do not play at that casino again. 

Nice! First time entering and first win! Top prize too. I think I have filled out the form correctly. What happens now? Have to wait for verification from casinos etc?