if the money was deposited, the IRS "washes its hand of it'. their view is 'tale it up with your bank'.
how do you know the money was direct deposited? and do you know whose bank account that is?
The way the stimulus payments worked is the IRS used the banking information from your 2019 tax return; otherwise checks were mailed.
if you werw a "non-filer" os that what you mean by "I filed through the mail" anad did you list a bank and account number of that form?
a lot more details required to help you. But the IRS will not get involved,