Victimized by SIM card swap scam; would like to engage T-mobile regarding aftermath

I have the same fraud with my mobile phone on Oct 3rd 2022.  I received the text from T-Mobile that my phone SIM has been assigned to a different phone.  This compromised the two factor authentication I have set on emails, Venmo, Robinhood and all financial accounts. Since hacker had control of my phone, they were able to change passwords and start financial transactions and transfers on various accounts.  Luckily I saw this on time and was able to reverse and get SIM assigned back to me.  This seems to be an insider in TMobile job otherwise how does SIM get transferred without approval though it needs PIN and text to Mobile phone to make any changes.  This is terrible.  I have written to Federal Communications Commission, for investigation in TMobile practices.  This is a broader issue at TMobile.