Child tax credit in US

Does anyone have any info on how this works? I've tried to call 4 times and get hung up on every time before ever making it off hold and the website isn't "able to verify my identity" despite 3 attempts to go through the ID me process and I've provided everything they ask for.

My oldest son's dad and I have joint custody. He claimed him on taxes this past year, as our custody agreement states he is supposed to. This next tax season is my turn to claim him. He won't tell me if he opted out of the early child tax credit refund and he's difficult to work with. I can't get in or ahold of anyone to change the information where he can't get the refunds that will be coming out of what is supposed to be my refund. I don't know what to do and just wanted to see if anyone had any knowledge on how this works. Will he get the refund even though it'll be coming out of my taxes? Is there anything I can do since I can't get ahold of anyone in the IRS?