Under age gambling

My 16 year old nephew used my bank card and my details to play in this black magic casino without being verified lost the money he said than he won they won’t let him withdraw it in the mean time they took £7000 of my money how they can let 16year old use there casino surely they should verify the person first before they let him play and also they have no number to contact only email and they let you withdraw the money and also they charge a transaction fees. Please can any one help I’m not going to rest till this issue is sorted I will report it to the whole world this casino is a con