My withdrawal and my cashback

I am sending you this as a formal complaint regarding the management of my account and the delay in refunding my money.
Specifically:
My account was closed without a clear and documented reason.
My winnings of €300 have been blocked/seized without sufficient explanation.
I was confirmed that €25 will be refunded to my bank account within 5–7 business days.
Today is the 12 business day and the amount has not been credited.
I have contacted them repeatedly via email without receiving any response.