blocked icloud

Dear Apple support team, could you please help me to unblock my Iphone, my 12 years old son bought Minecraft account on unknown website, when he logged other person's Icloud logged on default.Our phone got blocked and now it is just giving phone number to call, I called the person and he is asking money to give a password back.This is my phone and I have a box, so if I send serial number, could you help me? I have health problems and feel really bad, my sun keeps crying and it is really hard, even if I pay I am not sure if he gives me password. The account he is asking to send money is Russian. Please let me know if you have any questions

Thank you in advance

I really appreciate your support.Hope you will find the way to help me.