Childs college savings account

I have been separated for 6 months. STBX set up a savings account through ING for our son before we separated.
I logged on recently and found out he’s been withdrawing and transfering it into some other personal bank account. Is there nothing I can do to stop this?
I called ING to find out some information but since my name isn’t on the account they wouldn’t speak to me. I
am able to log onto their website though and see balance and all activity.

You may address this issue as part of equitable distribution, if he is removing the funds that were saved during the marriage for your son, and taking them for his own use, there is an argument that you should receive half those funds.