A few years ago someone managed to get into my account, somehow bypassing the 2SV. No clue how they did.
But last year when I got my PS5 I had to get a hold of PS to change my number as 2SV was still setup, I no longer had my ps4, and had a new phone. It wasn't bad for me. And was pretty straight forward. Sucky that you had the opposite experience. But at least you got your account back!
I think that if you can find the correct help section that will really streamline the process, I just got so frustrated that Sony, which is an absolutely massive company, hides their contact / help information so deeply in their support section.