Ask HN: How to protect against possible Identity Theft in motion

Hi HN, long time user but using a throwaway for obvious reasons. I think someone has been trying to get into my accounts starting with Credit Card account for now. Since Christmas, I have replaced my credit card twice which tells me that the credit company has BS security. But today I found out that supposedly someone called them as me and asked for a new card/PIN. To be fair, they did put an alert on my account and flagged it so that's nice but I am now worried if this person has access to more of my details including SSN etc.

I am reasonably wealthy (as a small business owner) and have decent amount of assets including almost a million in cash between personal and business accounts. I am very good with security in general (use secure passwords everywhere, keypassx, 2 FA whereever possible, alerts/notifications enabled on transasction etc).

But I am now really worried if someone is actively trying to get into my accounts. What are some of the additional steps I can take ? Note that I am not 100% sure yet but I want to be prepared in case.

Should I freeze my credit in case they have access to my SSN ? I read that credit agencies are a joke so not sure what precautions I can take ?