Fortune Play Casino - Unpaid cashback

Hi, hope you can help. I participated in a cashback promotion at Fortuneplay casino on the 18th of December. I made deposits totalling 69euro and as per the terms of the promo, I was supposed to receive 20% cashback (13.80 eur) the following day. The casino failed to pay the cashback and I have contacted them multiple times on chat where they appear to escalate the matter and tell me to contact them later for an update. I do this and there never is any update, in fact it's like the first time I contacted them each time. I've also emailed them about the issue and they did not bother responding. They don't seem to be disputing the matter but are also not doing anything about it. I'm attaching 1. Screenshot of promo email. 2. Screenshot of casino bonus history showing no cashback was added. I will forward on the promotion email as I cannot attach it. Grateful if you could escalate the matter. Thanks.